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  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Inferences Based on a Single Sample: Inferences Based on a Single Sample: Tests of HypothesisTests of Hypothesis

    8 8 -- 11

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Learning ObjectivesLearning Objectives

    1.1. Distinguish Types of Hypotheses Distinguish Types of Hypotheses

    2.2. Describe Hypothesis Testing ProcessDescribe Hypothesis Testing Process

    3.3. Explain pExplain p--Value ConceptValue Concept

    8 8 -- 22

    3.3. Explain pExplain p--Value ConceptValue Concept

    4.4. Solve Hypothesis Testing Problems Solve Hypothesis Testing Problems Based on a Single SampleBased on a Single Sample

    5.5. Explain Power of a TestExplain Power of a Test

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Statistical MethodsStatistical Methods

    StatisticalMethods

    8 8 -- 33

    DescriptiveStatistics

    InferentialStatistics

    EstimationHypothesis

    Testing

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Hypothesis Testing ConceptsHypothesis Testing Concepts

    8 8 -- 44

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Hypothesis TestingHypothesis Testing

    8 8 -- 55

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Hypothesis TestingHypothesis Testing

    PopulationPopulation

    8 8 -- 66

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Hypothesis TestingHypothesis Testing

    PopulationPopulation

    I believe the population mean age is 50 (hypothesis).

    8 8 -- 77

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Hypothesis TestingHypothesis Testing

    PopulationPopulation

    I believe the population mean age is 50 (hypothesis).

    8 8 -- 88

    MeanMeanX X = 20= 20

    Random Random samplesample

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Hypothesis TestingHypothesis Testing

    PopulationPopulation

    I believe the population mean age is 50 (hypothesis).

    Reject hypothesis! Not close.

    8 8 -- 99

    MeanMeanX X = 20= 20

    Random Random samplesample

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Whats a Hypothesis?Whats a Hypothesis?

    1.1. A Belief about a A Belief about a Population ParameterPopulation Parameter

    Parameter Is Parameter Is

    I believe the mean GPA I believe the mean GPA of this class is 3.5!of this class is 3.5!

    8 8 -- 1010

    Parameter Is Parameter Is PopulationPopulation Mean, Mean, Proportion, VarianceProportion, Variance

    Must Be StatedMust Be StatedBeforeBefore AnalysisAnalysis

    1984-1994 T/Maker Co.

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Null HypothesisNull Hypothesis

    1.1. What Is TestedWhat Is Tested

    2.2. Has Serious Outcome If Incorrect Has Serious Outcome If Incorrect Decision MadeDecision Made

    8 8 -- 1111

    3.3. Designated HDesignated H00 (Pronounced H(Pronounced H--noughtnought))

    4.4. Specified as HSpecified as H00: : Some Numeric Value Some Numeric Value Specified with = Sign Specified with = Sign , or , or Example, HExample, H00: : 33

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Alternative HypothesisAlternative Hypothesis

    1.1. Opposite of Null HypothesisOpposite of Null Hypothesis

    2.2. Always Has Inequality Sign:Always Has Inequality Sign: ,,, or , or 3.3. Designated HDesignated H

    8 8 -- 1212

    3.3. Designated HDesignated Haa4.4. Specified HSpecified Haa: : < Some Value< Some Value

    Example, HExample, Haa: : < 3< 3 will lead towill lead to twotwo--sided testssided tests will lead to one will lead to one--sided testssided tests

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Identifying HypothesesIdentifying HypothesesStepsSteps

    1.1. Example Problem: Test That the Example Problem: Test That the Population Mean Is Not 3Population Mean Is Not 3

    2.2. StepsSteps

    8 8 -- 1313

    2.2. StepsSteps State the Question Statistically (State the Question Statistically ( 3)3) State the Opposite Statistically (State the Opposite Statistically ( = 3)= 3)

    Must Be Mutually Exclusive & ExhaustiveMust Be Mutually Exclusive & Exhaustive

    Select the Alternative Hypothesis (Select the Alternative Hypothesis ( 3)3) Has the Has the , , SignSign

    State the Null Hypothesis (State the Null Hypothesis ( = 3)= 3)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    State the question statistically: State the question statistically: = 12= 12

    Is the population average amount of TV Is the population average amount of TV viewing 12 hours?viewing 12 hours?

    What Are the Hypotheses?What Are the Hypotheses?

    8 8 -- 1414

    State the opposite statistically: State the opposite statistically: 12 12 Select the alternative hypothesis: Select the alternative hypothesis: HHaa: : 1212State the null hypothesis: State the null hypothesis: HH00: : = 12= 12

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    State the question statistically: State the question statistically: 1212

    Is the population average amount of TV Is the population average amount of TV viewing viewing differentdifferent from 12 hours?from 12 hours?

    What Are the Hypotheses?What Are the Hypotheses?

    8 8 -- 1515

    State the opposite statistically: State the opposite statistically: = 12= 12Select the alternative hypothesis: Select the alternative hypothesis: HHaa: : 1212State the null hypothesis: State the null hypothesis: HH00: : = 12= 12

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    State the question statistically: State the question statistically: 2020

    Is the average cost per hat less than or Is the average cost per hat less than or equal to P20?equal to P20?

    What Are the Hypotheses?What Are the Hypotheses?

    8 8 -- 1616

    State the opposite statistically: State the opposite statistically: 2020Select the alternative hypothesis: Select the alternative hypothesis: HHaa: : 2020State the null hypothesis: State the null hypothesis: HH00: : 2020

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    State the question statistically: State the question statistically: 2525

    Is the average amount spent in the Is the average amount spent in the bookstore greater than P25?bookstore greater than P25?

    What Are the Hypotheses?What Are the Hypotheses?

    8 8 -- 1717

    State the opposite statistically: State the opposite statistically: 25 25 Select the alternative hypothesis: Select the alternative hypothesis: HHaa: : 2525State the null hypothesis: State the null hypothesis: HH00: : 2525

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Basic IdeaBasic Idea

    8 8 -- 1818

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Basic IdeaBasic Idea

    Sampling DistributionSampling Distribution

    8 8 -- 1919

    Sample Mean = 50HH00HH00

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Basic IdeaBasic Idea

    Sampling DistributionSampling Distribution

    It is unlikely It is unlikely that we would that we would get a sample get a sample

    8 8 -- 2020

    Sample Mean = 50

    mean of this mean of this value ...value ...

    20202020HH00HH00

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Basic IdeaBasic Idea

    Sampling DistributionSampling Distribution

    It is unlikely It is unlikely that we would that we would get a sample get a sample

    8 8 -- 2121

    Sample Mean = 50

    mean of this mean of this value ...value ...

    ... if in fact this were... if in fact this werethe population meanthe population mean

    20202020HH00HH00

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Basic IdeaBasic Idea

    Sampling DistributionSampling Distribution

    It is unlikely It is unlikely that we would that we would get a sample get a sample

    ... therefore, ... therefore, we reject the we reject the

    8 8 -- 2222

    Sample Mean = 50

    mean of this mean of this value ...value ...

    ... if in fact this were... if in fact this werethe population meanthe population mean

    hypothesis hypothesis that that = 50.= 50.

    20202020HH00HH00

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Level of SignificanceLevel of Significance

    1.1. ProbabilityProbability

    2.2. Defines Unlikely Values of Sample Defines Unlikely Values of Sample Statistic if Null Hypothesis Is TrueStatistic if Null Hypothesis Is True

    8 8 -- 2323

    Statistic if Null Hypothesis Is TrueStatistic if Null Hypothesis Is True Called Rejection Region of Sampling Called Rejection Region of Sampling

    DistributionDistribution

    3.3. Designated Designated (alpha)(alpha) Typical Values Are .01, .05, .10Typical Values Are .01, .05, .10

    4.4. Selected by Researcher at StartSelected by Researcher at Start

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Rejection Region Rejection Region (One(One--Tail Test) Tail Test)

    8 8 -- 2424

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Rejection Region Rejection Region (One(One--Tail Test) Tail Test)

    RejectionRegion

    Sampling DistributionSampling DistributionLevel of ConfidenceLevel of Confidence

    8 8 -- 2525

    HoValueCritical

    Value

    Sample Statistic

    NonrejectionRegion

    1 1 --

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Rejection Region Rejection Region (One(One--Tail Test) Tail Test)

    RejectionRegion

    Sampling DistributionSampling DistributionLevel of ConfidenceLevel of Confidence

    8 8 -- 2626

    HoValueCritical

    Value

    Sample Statistic

    NonrejectionRegion

    1 1 --

    Observed sample statisticObserved sample statistic

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Rejection Region Rejection Region (One(One--Tail Test) Tail Test)

    RejectionRegion

    Sampling DistributionSampling DistributionLevel of ConfidenceLevel of Confidence

    8 8 -- 2727

    HoValueCritical

    Value

    Sample Statistic

    NonrejectionRegion

    1 1 --

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Rejection Regions Rejection Regions (Two(Two--Tailed Test) Tailed Test)

    8 8 -- 2828

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Rejection Regions Rejection Regions (Two(Two--Tailed Test) Tailed Test)

    RejectionRegion

    RejectionRegion

    Sampling DistributionSampling DistributionLevel of ConfidenceLevel of Confidence

    8 8 -- 2929

    HoValue Critical

    ValueCriticalValue

    1/2 1/2

    Sample Statistic

    NonrejectionRegion

    1 1 --

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Rejection Regions Rejection Regions (Two(Two--Tailed Test) Tailed Test)

    RejectionRegion

    RejectionRegion

    Sampling DistributionSampling DistributionLevel of ConfidenceLevel of Confidence

    8 8 -- 3030

    HoValue Critical

    ValueCriticalValue

    1/2 1/2

    Sample Statistic

    NonrejectionRegion

    1 1 --

    Observed sample statisticObserved sample statistic

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Rejection Regions Rejection Regions (Two(Two--Tailed Test) Tailed Test)

    RejectionRegion

    RejectionRegion

    Sampling DistributionSampling DistributionLevel of ConfidenceLevel of Confidence

    8 8 -- 3131

    HoValue Critical

    ValueCriticalValue

    1/2 1/2

    Sample Statistic

    NonrejectionRegion

    1 1 --

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Rejection Regions Rejection Regions (Two(Two--Tailed Test) Tailed Test)

    RejectionRegion

    RejectionRegion

    Sampling DistributionSampling DistributionLevel of ConfidenceLevel of Confidence

    8 8 -- 3232

    HoValue Critical

    ValueCriticalValue

    1/2 1/2

    Sample Statistic

    NonrejectionRegion

    1 1 --

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Hypothesis Testing StepsHypothesis Testing Steps

    8 8 -- 3333

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    HH00 Testing StepsTesting Steps

    8 8 -- 3434

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    HH00 Testing StepsTesting Steps

    State HState H00

    State HState Haa

    Choose Choose

    8 8 -- 3535

    Choose Choose

    Choose Choose nn

    Choose testChoose test

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    HH00 Testing StepsTesting Steps

    Set up critical valuesSet up critical values

    Collect dataCollect data

    Compute test statisticCompute test statistic

    State HState H00

    State HState Haa

    Choose Choose

    8 8 -- 3636

    Compute test statisticCompute test statistic

    Make statistical decisionMake statistical decision

    Express decisionExpress decision

    Choose Choose

    Choose Choose nn

    Choose testChoose test

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    One Population TestsOne Population Tests

    OnePopulation

    8 8 -- 3737

    Z Test(1 & 2tail)

    t Test(1 & 2tail)

    Z Test(1 & 2tail)

    Mean Proportion Variance

    2 Test(1 & 2tail)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test of Mean (of Mean ( Known)Known)

    8 8 -- 3838

    of Mean (of Mean ( Known)Known)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    One Population TestsOne Population Tests

    OnePopulation

    8 8 -- 3939

    Z Test(1 & 2tail)

    t Test(1 & 2tail)

    Z Test(1 & 2tail)

    Mean Proportion Variance

    2 Test(1 & 2tail)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test for Mean (for Mean ( Known)Known)

    1.1. AssumptionsAssumptions Population Is Normally DistributedPopulation Is Normally Distributed

    If Not Normal, Can Be Approximated by If Not Normal, Can Be Approximated by Normal Distribution (Normal Distribution (nn 30)30)

    8 8 -- 4040

    Normal Distribution (Normal Distribution (nn 30)30)2.2. Alternative Hypothesis Has Alternative Hypothesis Has SignSign

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test for Mean (for Mean ( Known)Known)

    1.1. AssumptionsAssumptions Population Is Normally DistributedPopulation Is Normally Distributed

    If Not Normal, Can Be Approximated by If Not Normal, Can Be Approximated by Normal Distribution (Normal Distribution (nn 30)30)

    8 8 -- 4141

    Normal Distribution (Normal Distribution (nn 30)30)2.2. Alternative Hypothesis Has Alternative Hypothesis Has SignSign3.3. ZZ--Test StatisticTest Statistic

    ZX X

    n

    x

    x

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z TestTailed Z TestExample Example

    Does an average box of Does an average box of cereal contain cereal contain 368368 grams grams of cereal? A random of cereal? A random sample of sample of 2525 boxes boxes

    8 8 -- 4242

    sample of sample of 2525 boxes boxes showedshowedX = 372.5X = 372.5. The . The company has specified company has specified to be to be 2525 grams. Test at grams. Test at the the .05.05 level.level. 368 gm.368 gm.

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: :

    HHaa: :

    nn

    Test Statistic: Test Statistic:

    8 8 -- 4343

    nn Critical Value(s):Critical Value(s): Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 nn

    Test Statistic: Test Statistic:

    8 8 -- 4444

    nn Critical Value(s):Critical Value(s): Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 .05.05nn 2525

    Test Statistic: Test Statistic:

    8 8 -- 4545

    nn 2525Critical Value(s):Critical Value(s): Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 .05.05nn 2525

    Test Statistic: Test Statistic:

    8 8 -- 4646

    nn 2525Critical Value(s):Critical Value(s): Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 .05.05nn 2525

    Test Statistic: Test Statistic:

    ZX

    n

    372 5 368

    1525

    150.

    .

    8 8 -- 4747

    nn 2525Critical Value(s):Critical Value(s): Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

    n 25

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 .05.05nn 2525

    Test Statistic: Test Statistic:

    ZX

    n

    372 5 368

    1525

    150.

    .

    8 8 -- 4848

    nn 2525Critical Value(s):Critical Value(s): Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

    n 25

    Do not reject at Do not reject at = .05= .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 .05.05nn 2525

    Test Statistic: Test Statistic:

    ZX

    n

    372 5 368

    1525

    150.

    .

    8 8 -- 4949

    nn 2525Critical Value(s):Critical Value(s): Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

    n 25

    Do not reject at Do not reject at = .05= .05

    No evidence No evidence average is not 368average is not 368

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test Thinking ChallengeThinking Challenge

    Youre a Q/C inspector. You want to Youre a Q/C inspector. You want to find out if a new machine is making find out if a new machine is making electrical cords to customer electrical cords to customer specification: specification: averageaverage breaking breaking

    8 8 -- 5050

    specification: specification: averageaverage breaking breaking strength of strength of 7070 lb. with lb. with = 3.5= 3.5 lb. lb. You take a sample of You take a sample of 3636 cords & cords & compute a sample mean of compute a sample mean of 69.769.7 lb. lb. At the At the .05.05 level, is there evidence level, is there evidence that the machine is that the machine is notnot meeting the meeting the average breaking strength?average breaking strength?

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: :

    HHaa: :

    = = nn = =

    Test Statistic: Test Statistic:

    8 8 -- 5151

    nn = = Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 70= 70HHaa: : 7070 = = nn ==

    Test Statistic: Test Statistic:

    8 8 -- 5252

    nn ==Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 70= 70HHaa: : 7070 = = .05.05nn = = 3636

    Test Statistic: Test Statistic:

    8 8 -- 5353

    nn = = 3636Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 70= 70HHaa: : 7070 = = .05.05nn = = 3636

    Test Statistic: Test Statistic:

    8 8 -- 5454

    nn = = 3636Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 70= 70HHaa: : 7070 = = .05.05nn = = 3636

    Test Statistic: Test Statistic:

    ZX

    n

    69 7 70

    3 536

    51.

    ..

    8 8 -- 5555

    nn = = 3636Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

    n 36

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 70= 70HHaa: : 7070 = = .05.05nn = = 3636

    Test Statistic: Test Statistic:

    ZX

    n

    69 7 70

    3 536

    51.

    ..

    8 8 -- 5656

    nn = = 3636Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

    n 36

    Do not reject at Do not reject at = .05= .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 70= 70HHaa: : 7070 = = .05.05nn = = 3636

    Test Statistic: Test Statistic:

    ZX

    n

    69 7 70

    3 536

    51.

    ..

    8 8 -- 5757

    nn = = 3636Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

    n 36

    Do not reject at Do not reject at = .05= .05

    No evidence No evidence average is not 70average is not 70

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test of Mean (of Mean ( Known)Known)

    8 8 -- 5858

    of Mean (of Mean ( Known)Known)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test for Mean (for Mean ( Known)Known)

    1.1. AssumptionsAssumptions Population Is Normally DistributedPopulation Is Normally Distributed

    If Not Normal, Can Be Approximated by If Not Normal, Can Be Approximated by Normal Distribution (Normal Distribution (nn 30)30)

    8 8 -- 5959

    Normal Distribution (Normal Distribution (nn 30)30)2.2. Alternative Hypothesis Has < or > SignAlternative Hypothesis Has < or > Sign

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test for Mean (for Mean ( Known)Known)

    1.1. AssumptionsAssumptions Population Is Normally DistributedPopulation Is Normally Distributed

    If Not Normal, Can Be Approximated by If Not Normal, Can Be Approximated by Normal Distribution (Normal Distribution (nn 30)30)

    8 8 -- 6060

    Normal Distribution (Normal Distribution (nn 30)30)2.2. Alternative Hypothesis Has Alternative Hypothesis Has or > Signor > Sign3.3. ZZ--test Statistictest Statistic

    ZX X

    n

    x

    x

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test for Mean Hypothesesfor Mean Hypotheses

    8 8 -- 6161

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Reject H0

    OneOne--Tailed Z Test Tailed Z Test for Mean Hypothesesfor Mean Hypotheses

    HH00::==0 H0 Haa: :

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Reject H0Reject H0

    OneOne--Tailed Z Test Tailed Z Test for Mean Hypothesesfor Mean Hypotheses

    HH00::==0 H0 Haa: : > 00

    8 8 -- 6363

    Z0

    Z0

    Must be Must be significantlysignificantlybelow below

    Small values satisfy Small values satisfy HH0 0 . Dont reject!. Dont reject!

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test Finding Critical ZFinding Critical Z

    8 8 -- 6464

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    = 1

    OneOne--Tailed Z Test Tailed Z Test Finding Critical ZFinding Critical Z

    What Is Z given What Is Z given = .025?= .025?

    8 8 -- 6565

    Z0

    = .025= .025

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    = 1

    OneOne--Tailed Z Test Tailed Z Test Finding Critical ZFinding Critical Z

    .500 .500 -- .025.025

    What Is Z given What Is Z given = .025?= .025?

    8 8 -- 6666

    Z0

    -- .025.025.475.475

    = .025= .025

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Z .05 .07 = 1

    OneOne--Tailed Z Test Tailed Z Test Finding Critical ZFinding Critical Z

    .500 .500 -- .025.025 .06

    Standardized Normal Standardized Normal Probability Table (Portion)Probability Table (Portion)

    What Is Z given What Is Z given = .025?= .025?

    8 8 -- 6767

    1.6 .4505 .4515 .4525

    1.7 .4599 .4608 .4616

    1.8 .4678 .4686 .4693

    .4744 .4756

    Z0

    -- .025.025.475.475

    1.9 .4750.4750

    = .025= .025

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Z .05 .07 = 1

    OneOne--Tailed Z Test Tailed Z Test Finding Critical ZFinding Critical Z

    .500 .500 -- .025.025 .06.06

    Standardized Normal Standardized Normal Probability Table (Portion)Probability Table (Portion)

    What Is Z given What Is Z given = .025?= .025?

    8 8 -- 6868

    1.6 .4505 .4515 .4525

    1.7 .4599 .4608 .4616

    1.8 .4678 .4686 .4693

    .4744 .4756

    Z0 1.96

    -- .025.025.475.475

    1.91.9 .4750

    = .025= .025

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z TestTailed Z TestExample Example

    Does an average box of Does an average box of cereal contain cereal contain more thanmore than368368 grams of cereal? A grams of cereal? A random sample of random sample of 2525

    8 8 -- 6969

    random sample of random sample of 2525boxes showedboxes showedX = 372.5X = 372.5. . The company has The company has specified specified to be to be 2525grams. Test at the grams. Test at the .05.05level.level.

    368 gm.368 gm.

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: :

    HHaa: :

    = = n n = =

    Test Statistic: Test Statistic:

    8 8 -- 7070

    n n = =

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : > 368> 368 = = n n = =

    Test Statistic: Test Statistic:

    8 8 -- 7171

    n n = =

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : > 368> 368 = = .05.05n n = = 2525

    Test Statistic: Test Statistic:

    8 8 -- 7272

    n n = = 2525

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : > 368> 368 = = .05.05n n = = 2525

    Test Statistic: Test Statistic:

    8 8 -- 7373

    n n = = 2525

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.645

    .05

    Reject

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : > 368> 368 = = .05.05n n = = 2525

    Test Statistic: Test Statistic:

    ZX

    n

    372 5 368

    1525

    150.

    .

    8 8 -- 7474

    n n = = 2525

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.645

    .05

    Reject

    n 25

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : > 368> 368 = = .05.05n n = = 2525

    Test Statistic: Test Statistic:

    ZX

    n

    372 5 368

    1525

    150.

    .

    8 8 -- 7575

    n n = = 2525

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.645

    .05

    Reject

    n 25

    Do not reject at Do not reject at = .05= .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test SolutionSolution

    HH00: : = 368= 368HHaa: : > 368> 368 = = .05.05n n = = 2525

    Test Statistic: Test Statistic:

    ZX

    n

    372 5 368

    1525

    150.

    .

    8 8 -- 7676

    n n = = 2525

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.645

    .05

    Reject

    n 25

    Do not reject at Do not reject at = .05= .05

    No evidence average No evidence average is more than 368is more than 368

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test Thinking ChallengeThinking Challenge

    Youre an analyst for Ford. You Youre an analyst for Ford. You want to find out if the average want to find out if the average miles per gallon of Escorts is at miles per gallon of Escorts is at least 32 mpg. Similar models least 32 mpg. Similar models

    8 8 -- 7777

    least 32 mpg. Similar models least 32 mpg. Similar models have a standard deviation of have a standard deviation of 3.83.8mpg. You take a sample of mpg. You take a sample of 6060Escorts & compute a sample Escorts & compute a sample mean of mean of 30.730.7 mpg. At the mpg. At the .01.01level, is there evidence that the level, is there evidence that the miles per gallon is miles per gallon is at leastat least 3232??

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: :

    HHaa: :

    = = nn ==

    Test Statistic: Test Statistic: Test Statistic: Test Statistic:

    8 8 -- 7878

    nn ==

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 32= 32HHaa: : < 32< 32 = = nn ==

    Test Statistic: Test Statistic: Test Statistic: Test Statistic:

    8 8 -- 7979

    nn ==

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 32= 32HHaa: : < 32< 32 == .01.01nn = = 6060

    Test Statistic: Test Statistic: Test Statistic: Test Statistic:

    8 8 -- 8080

    nn = = 6060

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 32= 32HHaa: : < 32< 32 = .01= .01nn = 60= 60

    Test Statistic: Test Statistic: Test Statistic: Test Statistic:

    8 8 -- 8181

    nn = 60= 60

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Decision:Decision:

    Conclusion:Conclusion:

    Z0-2.33

    .01

    Reject

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 32= 32HHaa: : < 32< 32 = .01= .01nn = 60= 60

    Test Statistic: Test Statistic: Test Statistic: Test Statistic:

    ZX

    n

    30 7 32

    3 860

    2 65.

    ..

    8 8 -- 8282

    nn = 60= 60

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Decision:Decision:

    Conclusion:Conclusion:

    Z0-2.33

    .01

    Reject

    n 60

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 32= 32HHaa: : < 32< 32 = .01= .01nn = 60= 60

    Test Statistic: Test Statistic: Test Statistic: Test Statistic:

    ZX

    n

    30 7 32

    3 860

    2 65.

    ..

    8 8 -- 8383

    nn = 60= 60

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Decision:Decision:

    Conclusion:Conclusion:

    Z0-2.33

    .01

    Reject

    n 60

    Reject at Reject at = .01= .01

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test Solution*Solution*

    HH00: : = 32= 32HHaa: : < 32< 32 = .01= .01nn = 60= 60

    Test Statistic: Test Statistic: Test Statistic: Test Statistic:

    ZX

    n

    30 7 32

    3 860

    2 65.

    ..

    8 8 -- 8484

    nn = 60= 60

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Decision:Decision:

    Conclusion:Conclusion:

    Z0-2.33

    .01

    Reject

    n 60

    Reject at Reject at = .01= .01

    There is evidence There is evidence average is less than 32average is less than 32

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Decision Making RisksDecision Making Risks

    8 8 -- 8585

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Errors in Errors in Making DecisionMaking Decision

    1.1. Type I ErrorType I Error Reject True Null HypothesisReject True Null Hypothesis Has Serious ConsequencesHas Serious Consequences

    Probability of Type I Error Is Probability of Type I Error Is (Alpha)(Alpha)

    8 8 -- 8686

    Probability of Type I Error Is Probability of Type I Error Is (Alpha)(Alpha)Called Level of SignificanceCalled Level of Significance

    2.2. Type II ErrorType II Error Do Not Reject False Null HypothesisDo Not Reject False Null Hypothesis Probability of Type II Error Is Probability of Type II Error Is (Beta)(Beta)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Jury Trial H0 Test

    Actual Situation Actual Situation

    Verdict Innocent Guilty Decision H0 True H0

    Decision ResultsDecision Results

    HH00: Innocent: Innocent

    8 8 -- 8787

    Verdict Innocent Guilty Decision H0 True H0False

    Innocent Correct ErrorDo NotReject

    H0

    1 - Type IIError

    ()

    Guilty Error Correct RejectH0

    Type IError () Power(1 - )

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Jury Trial H0 Test

    Actual Situation Actual Situation

    Verdict Innocent Guilty Decision H0 True H0

    Decision ResultsDecision Results

    HH00: Innocent: Innocent

    8 8 -- 8888

    Verdict Innocent Guilty Decision H0 True H0False

    Innocent Correct Error AcceptH0

    1 - Type IIError

    ()

    Guilty Error Correct RejectH0

    Type IError () Power(1 - )

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    & & Have an Have an Inverse RelationshipInverse Relationship

    You cant reduce both errors simultaneously!

    8 8 -- 8989

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Factors Affecting Factors Affecting 1.1. True Value of Population ParameterTrue Value of Population Parameter

    Increases When Difference With Hypothesized Increases When Difference With Hypothesized Parameter DecreasesParameter Decreases

    2.2. Significance Level, Significance Level,

    8 8 -- 9090

    2.2. Significance Level, Significance Level, Increases When Increases When DecreasesDecreases

    3.3. Population Standard Deviation, Population Standard Deviation, Increases When Increases When Increases Increases

    4.4. Sample Size, Sample Size, nn

    Increases When Increases When nn DecreasesDecreases

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Exercise 8.15Exercise 8.15

    1000 subjects1000 subjects

    500 told truth, 500 lied500 told truth, 500 lied

    Lie detector says Lie detector says

    8 8 -- 9191

    185 truth tellers were liars185 truth tellers were liars

    120 liars were truth tellers120 liars were truth tellers

    Ho: truth tellerHo: truth teller

    a)a) What is a typeWhat is a type--I error? TypeI error? Type--II error?II error?

    b)b) What is Pr(typeWhat is Pr(type--I error)? Pr(typeI error)? Pr(type--II error)?II error)?

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Observed Significance Observed Significance Levels: pLevels: p--ValuesValues

    8 8 -- 9292

    Levels: pLevels: p--ValuesValues

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    pp--ValueValue

    1.1. Probability of Obtaining a Test Statistic Probability of Obtaining a Test Statistic More Extreme (More Extreme (or or than Actual than Actual Sample Value Given HSample Value Given H00 Is True Is True

    8 8 -- 9393

    2.2. Called Observed Level of SignificanceCalled Observed Level of Significance Smallest Value of Smallest Value of HH00 Can Be RejectedCan Be Rejected

    3.3. Used to Make Rejection DecisionUsed to Make Rejection Decision If pIf p--Value Value , Do Not Reject H, Do Not Reject H00 If pIf p--Value < Value < , Reject H, Reject H00

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test pp--Value Example Value Example

    Does an average box of Does an average box of cereal contain cereal contain 368368 grams grams of cereal? A random of cereal? A random sample of sample of 2525 boxes boxes

    8 8 -- 9494

    sample of sample of 2525 boxes boxes showedshowedX = 372.5X = 372.5. The . The company has specified company has specified to be to be 2525 grams. Find the grams. Find the pp--Value.Value. 368 gm.368 gm.

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    8 8 -- 9595

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    ZX

    n

    372 5 368

    1525

    150.

    .

    8 8 -- 9696

    Z0 1.50-1.50

    Z value of sample Z value of sample statistic (observed)statistic (observed)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    pp--value is P(Z value is P(Z --1.50 or Z 1.50 or Z 1.50)1.50)

    8 8 -- 9797

    Z0 1.50-1.50

    Z value of sample Z value of sample statistic (observed)statistic (observed)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    1/2 p-Value1/2 p-Value

    pp--value is P(Z value is P(Z --1.50 or Z 1.50 or Z 1.50)1.50)

    8 8 -- 9898

    Z0 1.50-1.50

    Z value of sample Z value of sample statistic (observed)statistic (observed)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    1/2 p-Value1/2 p-Value

    pp--value is P(Z value is P(Z --1.50 or Z 1.50 or Z 1.50)1.50)

    8 8 -- 9999

    Z0 1.50-1.50

    Z value of sample Z value of sample statistic (observed)statistic (observed)

    From Z table: From Z table: lookup 1.50lookup 1.50

    .4332.4332

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    1/2 p-Value1/2 p-Value.5000.5000

    pp--value is P(Z value is P(Z --1.50 or Z 1.50 or Z 1.50)1.50)

    8 8 -- 100100

    Z0 1.50-1.50

    Z value of sample Z value of sample statistic (observed)statistic (observed)

    From Z table: From Z table: lookup 1.50lookup 1.50

    .4332.4332

    .5000.5000-- .4332.4332

    .0668.0668

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    1/2 p-Value.0668

    1/2 p-Value.0668

    pp--value is P(Z value is P(Z --1.50 or Z 1.50 or Z 1.50) = 1.50) = .1336.1336

    .5000.5000

    8 8 -- 101101

    Z0 1.50-1.50

    .0668.0668

    Z value of sample Z value of sample statisticstatistic

    From Z table: From Z table: lookup 1.50lookup 1.50

    .4332.4332

    .5000.5000-- .4332.4332

    .0668.0668

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    RejectReject

    1/2 p1/2 p--Value = .0668Value = .06681/2 p1/2 p--Value = .0668Value = .0668

    8 8 -- 102102

    0 1.50-1.50 Z

    RejectReject

    1/2 1/2 = .025= .0251/2 1/2 = .025= .025

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    RejectReject

    (p(p--Value = .1336) Value = .1336) (( = .05). = .05). Do not reject.Do not reject.

    1/2 p1/2 p--Value = .0668Value = .06681/2 p1/2 p--Value = .0668Value = .0668

    8 8 -- 103103

    0 1.50-1.50 Z

    RejectReject

    1/2 1/2 = .025= .0251/2 1/2 = .025= .025

    Test statistic is in Do not reject regionTest statistic is in Do not reject region

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test pp--Value Example Value Example

    Does an average box of Does an average box of cereal contain cereal contain more thanmore than368368 grams of cereal? A grams of cereal? A random sample of random sample of 2525

    8 8 -- 104104

    random sample of random sample of 2525boxes showedboxes showedX = 372.5X = 372.5. . The company has The company has specified specified to be to be 2525grams. Find the pgrams. Find the p--Value.Value. 368 gm.368 gm.

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    8 8 -- 105105

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    ZX

    n

    372 5 368

    1525

    150.

    .

    8 8 -- 106106

    Z0 1.50

    Z value of sample Z value of sample statisticstatistic

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    p-ValueUse Use

    pp--Value is P(Z Value is P(Z 1.50) 1.50)

    8 8 -- 107107

    Z0 1.50

    p-ValueUse Use alternative alternative hypothesis hypothesis to find to find directiondirection

    Z value of sample Z value of sample statisticstatistic

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    p-ValueUse Use

    pp--Value is P(Z Value is P(Z 1.50) 1.50)

    8 8 -- 108108

    Z0 1.50

    p-ValueUse Use alternative alternative hypothesis hypothesis to find to find directiondirection

    Z value of sample Z value of sample statisticstatistic

    From Z table: From Z table: lookup 1.50lookup 1.50

    .4332.4332

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    p-ValueUse Use

    pp--Value is P(Z Value is P(Z 1.50) 1.50)

    8 8 -- 109109

    Z0 1.50

    p-ValueUse Use alternative alternative hypothesis hypothesis to find to find directiondirection

    Z value of sample Z value of sample statisticstatistic

    From Z table: From Z table: lookup 1.50lookup 1.50

    .4332.4332

    .5000.5000-- .4332.4332

    .0668.0668

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    p-Value.0668Use Use

    pp--Value is P(Z Value is P(Z 1.50) = .06681.50) = .0668

    8 8 -- 110110

    Z0 1.50

    .0668

    Z value of sample Z value of sample statisticstatistic

    From Z table: From Z table: lookup 1.50lookup 1.50

    .4332.4332

    Use Use alternative alternative hypothesis hypothesis to find to find directiondirection

    .5000.5000-- .4332.4332

    .0668.0668

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    Reject

    pp--Value = .0668Value = .0668

    8 8 -- 111111

    0 1.50 Z

    Reject

    = .05= .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed Z Test Tailed Z Test pp--Value SolutionValue Solution

    Reject

    (p(p--Value = .0668) Value = .0668) (( = .05). = .05). Do not reject.Do not reject.

    pp--Value = .0668Value = .0668

    8 8 -- 112112

    0 1.50 Z

    Reject

    = .05= .05

    Test statistic is in Do not reject regionTest statistic is in Do not reject region

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    pp--Value Value Thinking ChallengeThinking Challenge

    Youre an analyst for Ford. You Youre an analyst for Ford. You want to find out if the average want to find out if the average miles per gallon of Escorts is miles per gallon of Escorts is at at least 32 least 32 mpg. Similar models mpg. Similar models

    8 8 -- 113113

    least 32 least 32 mpg. Similar models mpg. Similar models have a standard deviation of have a standard deviation of 3.83.8mpg. You take a sample of mpg. You take a sample of 6060Escorts & compute a sample Escorts & compute a sample mean of mean of 30.730.7 mpg. What is the mpg. What is the value of the observed level of value of the observed level of significance (significance (pp--ValueValue)?)?

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    pp--Value Value Solution*Solution*

    p-Value.004Use Use .5000.5000

    pp--Value is P(Z Value is P(Z --2.65) = .004.2.65) = .004.pp--Value < (Value < ( = .01). Reject H= .01). Reject H00..

    8 8 -- 114114

    Z0-2.65

    .004

    Z value of Z value of sample statisticsample statistic

    From Z table: From Z table: lookup 2.65lookup 2.65

    .4960.4960

    Use Use alternative alternative hypothesis hypothesis to find to find directiondirection

    .5000.5000-- .4960.4960

    .0040.0040

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test of Mean (of Mean ( Unknown)Unknown)

    8 8 -- 115115

    of Mean (of Mean ( Unknown)Unknown)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    One Population TestsOne Population Tests

    OnePopulation

    8 8 -- 116116

    Z Test(1 & 2tail)

    t Test(1 & 2tail)

    Z Test(1 & 2tail)

    Mean Proportion Variance

    2 Test(1 & 2tail)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    t Test for Mean t Test for Mean (( Unknown)Unknown)

    1.1. AssumptionsAssumptions Population Is Normally DistributedPopulation Is Normally Distributed

    If Not Normal, Only Slightly Skewed & If Not Normal, Only Slightly Skewed & Large Sample (Large Sample (nn 30) Taken30) Taken

    8 8 -- 117117

    Large Sample (Large Sample (nn 30) Taken30) Taken2.2. Parametric Test ProcedureParametric Test Procedure

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    t Test for Mean t Test for Mean (( Unknown)Unknown)

    1.1. AssumptionsAssumptions Population Is Normally DistributedPopulation Is Normally Distributed

    If Not Normal, Only Slightly Skewed & If Not Normal, Only Slightly Skewed & Large Sample (Large Sample (nn 30) Taken30) Taken

    8 8 -- 118118

    Large Sample (Large Sample (nn 30) Taken30) Taken2.2. Parametric Test ProcedureParametric Test Procedure

    3.3. t Test Statistict Test Statistic

    tX

    Sn

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t TestTailed t TestFinding Critical t ValuesFinding Critical t Values

    8 8 -- 119119

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t TestTailed t TestFinding Critical t ValuesFinding Critical t Values

    Given: n = 3; Given: n = 3; = .10= .10

    8 8 -- 120120

    t0

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t TestTailed t TestFinding Critical t ValuesFinding Critical t Values

    Given: n = 3; Given: n = 3; = .10= .10

    8 8 -- 121121

    t0

    /2 = .05/2 = .05

    /2 = .05/2 = .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t TestTailed t TestFinding Critical t ValuesFinding Critical t Values

    Given: n = 3; Given: n = 3; = .10= .10

    df = n df = n -- 1 = 21 = 2

    8 8 -- 122122

    t0

    /2 = .05/2 = .05

    /2 = .05/2 = .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    v t.10 t.05 t.025

    TwoTwo--Tailed t TestTailed t TestFinding Critical t ValuesFinding Critical t Values

    Critical Values of t Table Critical Values of t Table (Portion)(Portion)

    Given: n = 3; Given: n = 3; = .10= .10

    df = n df = n -- 1 = 1 = 22

    8 8 -- 123123

    v t.10 t.05 t.025

    1 3.078 6.314 12.706

    2 1.886 2.920 4.303

    3 1.638 2.353 3.182t0

    /2 = /2 = .05.05

    /2 = .05/2 = .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    v t.10 t.05 t.025

    TwoTwo--Tailed t TestTailed t TestFinding Critical t ValuesFinding Critical t Values

    Critical Values of t Table Critical Values of t Table (Portion)(Portion)

    Given: n = 3; Given: n = 3; = .10= .10

    df = n df = n -- 1 = 21 = 2

    8 8 -- 124124

    v t.10 t.05 t.025

    1 3.078 6.314 12.706

    2 1.886 2.920 4.303

    3 1.638 2.353 3.182t0 2.920-2.920

    /2 = .05/2 = .05

    /2 = .05/2 = .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t TestTailed t TestExample Example

    Does an average box of Does an average box of cereal contain cereal contain 368368grams of cereal? A grams of cereal? A random sample of random sample of 3636

    8 8 -- 125125

    random sample of random sample of 3636boxes had a mean of boxes had a mean of 372.5372.5 & a standard & a standard deviation ofdeviation of 1212 grams. grams. Test at the Test at the .05.05 level.level. 368 gm.368 gm.

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test SolutionSolution

    HH00: :

    HHaa: :

    = = df = df =

    Test Statistic: Test Statistic:

    8 8 -- 126126

    df = df = Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 = = df = df =

    Test Statistic: Test Statistic:

    8 8 -- 127127

    df = df = Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 = = .05.05df = df = 36 36 -- 1 = 351 = 35

    Test Statistic: Test Statistic:

    8 8 -- 128128

    df = df = 36 36 -- 1 = 351 = 35Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 = = .05.05df = df = 36 36 -- 1 = 351 = 35

    Test Statistic: Test Statistic:

    8 8 -- 129129

    df = df = 36 36 -- 1 = 351 = 35Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    t0 2.0301-2.0301

    .025

    Reject H0 Reject H0

    .025

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 = = .05.05df = df = 36 36 -- 1 = 351 = 35

    Test Statistic: Test Statistic:

    tX

    Sn

    372 5 3681236

    2 25.

    .

    8 8 -- 130130

    df = df = 36 36 -- 1 = 351 = 35Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    t0 2.0301-2.0301

    .025

    Reject H0 Reject H0

    .025

    n 36

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 = = .05.05df = df = 36 36 -- 1 = 351 = 35

    Test Statistic: Test Statistic:

    tX

    Sn

    372 5 3681236

    2 25.

    .

    8 8 -- 131131

    df = df = 36 36 -- 1 = 351 = 35Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    t0 2.0301-2.0301

    .025

    Reject H0 Reject H0

    .025

    n 36

    Reject at Reject at = .05= .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 368= 368HHaa: : 368368 = = .05.05df = df = 36 36 -- 1 = 351 = 35

    Test Statistic: Test Statistic:

    tX

    Sn

    372 5 3681236

    2 25.

    .

    8 8 -- 132132

    df = df = 36 36 -- 1 = 351 = 35Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    t0 2.0301-2.0301

    .025

    Reject H0 Reject H0

    .025

    n 36

    Reject at Reject at = .05= .05

    There is evidence pop. There is evidence pop. average is not 368average is not 368

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t TestTailed t TestThinking ChallengeThinking Challenge

    You work for the FTC. A You work for the FTC. A manufacturer of detergent manufacturer of detergent claims that the mean weight claims that the mean weight of detergent is of detergent is 3.253.25 lb. You lb. You

    8 8 -- 133133

    of detergent is of detergent is 3.253.25 lb. You lb. You take a random sample of take a random sample of 6464containers. You calculate the containers. You calculate the sample average to be sample average to be 3.2383.238lb. with a standard deviation lb. with a standard deviation of of .117.117 lb. At the lb. At the .01.01 level, is level, is the manufacturer correct?the manufacturer correct?

    3.25 lb.3.25 lb.

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test Solution*Solution*

    HH00: :

    HHaa: :

    df df

    Test Statistic: Test Statistic:

    8 8 -- 134134

    df df Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 3.25= 3.25HHaa: : 3.253.25 df df

    Test Statistic: Test Statistic:

    8 8 -- 135135

    df df Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 3.25= 3.25HHaa: : 3.253.25 .01.01df df 64 64 -- 1 = 631 = 63

    Test Statistic: Test Statistic:

    8 8 -- 136136

    df df 64 64 -- 1 = 631 = 63Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 3.25= 3.25HHaa: : 3.253.25 .01.01df df 64 64 -- 1 = 631 = 63

    Test Statistic: Test Statistic:

    8 8 -- 137137

    df df 64 64 -- 1 = 631 = 63Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    t0 2.6561-2.6561

    .005

    Reject H0 Reject H0

    .005

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 3.25= 3.25HHaa: : 3.253.25 .01.01df df 64 64 -- 1 = 631 = 63

    Test Statistic: Test Statistic:

    tX

    Sn

    3 238 3 2511764

    82. .

    ..

    8 8 -- 138138

    df df 64 64 -- 1 = 631 = 63Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    t0 2.6561-2.6561

    .005

    Reject H0 Reject H0

    .005

    n 64

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 3.25= 3.25HHaa: : 3.253.25 .01.01df df 64 64 -- 1 = 631 = 63

    Test Statistic: Test Statistic:

    tX

    Sn

    3 238 3 2511764

    82. .

    ..

    8 8 -- 139139

    df df 64 64 -- 1 = 631 = 63Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    t0 2.6561-2.6561

    .005

    Reject H0 Reject H0

    .005

    n 64

    Do not reject at Do not reject at = .01= .01

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    TwoTwo--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 3.25= 3.25HHaa: : 3.253.25 .01.01df df 64 64 -- 1 = 631 = 63

    Test Statistic: Test Statistic:

    tX

    Sn

    3 238 3 2511764

    82. .

    ..

    8 8 -- 140140

    df df 64 64 -- 1 = 631 = 63Critical Value(s):Critical Value(s):

    Decision:Decision:

    Conclusion:Conclusion:

    t0 2.6561-2.6561

    .005

    Reject H0 Reject H0

    .005

    n 64

    Do not reject at Do not reject at = .01= .01

    There is no evidence There is no evidence average is not 3.25average is not 3.25

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test of Mean (of Mean ( Unknown)Unknown)

    8 8 -- 141141

    of Mean (of Mean ( Unknown)Unknown)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t TestTailed t TestExample Example

    Is the average capacity of Is the average capacity of batteries batteries at least 140 at least 140 ampereampere--hours? A random hours? A random sample of sample of 2020 batteries had batteries had

    8 8 -- 142142

    sample of sample of 2020 batteries had batteries had a mean of a mean of 138.47138.47 & a & a standard deviation of standard deviation of 2.662.66. . Assume a normal Assume a normal distribution. Test at the distribution. Test at the .05.05level.level.

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test SolutionSolution

    HH00: :

    HHaa: :

    ==df =df =

    Test Statistic: Test Statistic:

    8 8 -- 143143

    df =df =

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 140= 140HHaa: : < 140< 140 = = df = df =

    Test Statistic: Test Statistic:

    8 8 -- 144144

    df = df =

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 140= 140HHaa: : < 140< 140 = = .05.05df = df = 20 20 -- 1 = 191 = 19

    Test Statistic: Test Statistic:

    8 8 -- 145145

    df = df = 20 20 -- 1 = 191 = 19

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 140= 140HHaa: : < 140< 140 = = .05.05df = df = 20 20 -- 1 = 191 = 19

    Test Statistic: Test Statistic:

    8 8 -- 146146

    t0-1.7291

    .05

    Reject

    df = df = 20 20 -- 1 = 191 = 19

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 140= 140HHaa: : < 140< 140 = = .05.05df = df = 20 20 -- 1 = 191 = 19

    Test Statistic: Test Statistic:

    tX

    Sn

    138 47 1402 66

    20

    2 57.

    ..

    8 8 -- 147147

    t0-1.7291

    .05

    Reject

    df = df = 20 20 -- 1 = 191 = 19

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    n 20

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 140= 140HHaa: : < 140< 140 = = .05.05df = df = 20 20 -- 1 = 191 = 19

    Test Statistic: Test Statistic:

    tX

    Sn

    138 47 1402 66

    20

    2 57.

    ..

    8 8 -- 148148

    t0-1.7291

    .05

    Reject

    df = df = 20 20 -- 1 = 191 = 19

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    n 20

    Reject at Reject at = .05= .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test SolutionSolution

    HH00: : = 140= 140HHaa: : < 140< 140 = = .05.05df = df = 20 20 -- 1 = 191 = 19

    Test Statistic: Test Statistic:

    tX

    Sn

    138 47 1402 66

    20

    2 57.

    ..

    8 8 -- 149149

    t0-1.7291

    .05

    Reject

    df = df = 20 20 -- 1 = 191 = 19

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    n 20

    Reject at Reject at = .05= .05

    There is evidence pop. There is evidence pop. average is less than 140average is less than 140

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t TestTailed t TestThinking ChallengeThinking Challenge

    Youre a marketing analyst for Youre a marketing analyst for WalWal--Mart. WalMart. Wal--Mart had teddy Mart had teddy bears on sale last week. The bears on sale last week. The weekly sales ($ 00) of bears weekly sales ($ 00) of bears

    8 8 -- 150150

    weekly sales ($ 00) of bears weekly sales ($ 00) of bears sold in sold in 1010 stores was:stores was: 8 11 0 8 11 0 4 7 8 10 5 8 34 7 8 10 5 8 3. . At the At the .05.05 level, is there level, is there evidence that the average bear evidence that the average bear sales per store is sales per store is moremore thanthan 5 5 ($ 00)?($ 00)?

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test Solution*Solution*

    HH00: :

    HHaa: :

    = = df = df =

    Test Statistic: Test Statistic:

    8 8 -- 151151

    df = df =

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 5= 5HHaa: : > 5> 5 = = df =df =

    Test Statistic: Test Statistic:

    8 8 -- 152152

    df =df =

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 5= 5HHaa: : > 5> 5 = = .05.05df = df = 10 10 -- 1 = 91 = 9

    Test Statistic: Test Statistic:

    8 8 -- 153153

    df = df = 10 10 -- 1 = 91 = 9

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 5= 5HHaa: : > 5> 5 = = .05.05df = df = 10 10 -- 1 = 91 = 9

    Test Statistic: Test Statistic:

    8 8 -- 154154

    t0 1.8331

    .05

    Reject

    df = df = 10 10 -- 1 = 91 = 9

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 5= 5HHaa: : > 5> 5 = = .05.05df = df = 10 10 -- 1 = 91 = 9

    Test Statistic: Test Statistic:

    tX

    Sn

    6 4 53 373

    10

    131..

    .

    8 8 -- 155155

    t0 1.8331

    .05

    Reject

    df = df = 10 10 -- 1 = 91 = 9

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    n 10

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 5= 5HHaa: : > 5> 5 = = .05.05df = df = 10 10 -- 1 = 91 = 9

    Test Statistic: Test Statistic:

    tX

    Sn

    6 4 53 373

    10

    131..

    .

    8 8 -- 156156

    t0 1.8331

    .05

    Reject

    df = df = 10 10 -- 1 = 91 = 9

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    n 10

    Do not reject at Do not reject at = .05= .05

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Tailed t Test Tailed t Test Solution*Solution*

    HH00: : = 5= 5HHaa: : > 5> 5 = = .05.05df = df = 10 10 -- 1 = 91 = 9

    Test Statistic: Test Statistic:

    tX

    Sn

    6 4 53 373

    10

    131..

    .

    8 8 -- 157157

    t0 1.8331

    .05

    Reject

    df = df = 10 10 -- 1 = 91 = 9

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    n 10

    Do not reject at Do not reject at = .05= .05

    There is no evidence There is no evidence average is more than 5average is more than 5

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Z Test of ProportionZ Test of Proportion

    8 8 -- 158158

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Data TypesData Types

    Data

    8 8 -- 159159

    Numerical Qualitative

    Discrete Continuous

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    1.1. Approximated by Approximated by Normal DistributionNormal Distribution

    Excludes 0 or nExcludes 0 or n

    Sampling Distribution Sampling Distribution of Proportionof Proportion

    Sampling DistributionSampling Distribution

    .2.2

    .3.3P(PP(P^^ )) 13 ppnpn

    8 8 -- 160160

    pp

    Excludes 0 or nExcludes 0 or n

    2.2. MeanMean

    3.3. Standard ErrorStandard Error

    P p

    where where pp00 = Population Proportion= Population Proportionpp^^pp

    nn 11

    .0.0

    .1.1

    .2.2

    .0.0 .2.2 .4.4 .6.6 .8.8 1.01.0

    PP^^

    00 00

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Standardizing Sampling Standardizing Sampling Distribution of ProportionDistribution of Proportion

    Sampling Sampling DistributionDistribution

    Standardized Standardized Normal DistributionNormal Distribution

    ZZpp pp pp

    pp pp

    nn

    ^^pp

    pp

    ^^

    ^^

    (( ))11

    ^^00

    00 00

    8 8 -- 161161

    Z Z = 0= 0

    zz= 1= 1

    ZZ

    DistributionDistribution Normal DistributionNormal Distribution

    PP^^PP

    PP

    ^^

    ^^

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    One Population TestsOne Population Tests

    OnePopulation

    8 8 -- 162162

    Z Test(1 & 2tail)

    t Test(1 & 2tail)

    Z Test(1 & 2tail)

    Mean Proportion Variance

    2 Test(1 & 2tail)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Sample Z Test Sample Z Test for Proportionfor Proportion

    8 8 -- 163163

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Sample Z Test Sample Z Test for Proportionfor Proportion

    1.1. AssumptionsAssumptions Two Categorical OutcomesTwo Categorical Outcomes

    Population Follows Binomial DistributionPopulation Follows Binomial Distribution

    8 8 -- 164164

    Normal Approximation Can Be UsedNormal Approximation Can Be Used

    Does Not Contain 0 or nDoes Not Contain 0 or n 13 ppnpn

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Sample Z Test Sample Z Test for Proportionfor Proportion

    1.1. AssumptionsAssumptions Two Categorical OutcomesTwo Categorical Outcomes

    Population Follows Binomial DistributionPopulation Follows Binomial Distribution

    8 8 -- 165165

    Normal Approximation Can Be UsedNormal Approximation Can Be Used

    Does Not Contain 0 or nDoes Not Contain 0 or n

    2.2. ZZ--test statistic for proportiontest statistic for proportion

    Zp p

    p pn

    ( )0

    0 01Hypothesized Hypothesized population proportionpopulation proportion

    13 ppnpn

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test Example Example

    The present packaging The present packaging system produces system produces 10%10%defective cereal boxes. defective cereal boxes. Using a new system, a Using a new system, a

    8 8 -- 166166

    Using a new system, a Using a new system, a random sample of random sample of 200200boxes hadboxes had1111 defects. defects. Does the new system Does the new system produce produce fewerfewer defects? defects? Test at the Test at the .05.05 level.level.

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test SolutionSolution

    HH00: :

    HHaa: :

    = = nn ==

    Test Statistic: Test Statistic:

    8 8 -- 167167

    nn ==

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test SolutionSolution

    HH00: : pp = .10= .10

    HHaa: : pp < .10< .10

    = = nn = =

    Test Statistic: Test Statistic:

    8 8 -- 168168

    nn = =

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test SolutionSolution

    HH00: : pp ==.10.10HHaa: : pp < .10< .10

    = = .05.05nn = = 200200

    Test Statistic: Test Statistic:

    8 8 -- 169169

    nn = = 200200

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test SolutionSolution

    HH00: : pp = .10= .10

    HHaa: : pp < .10< .10

    = = .05.05nn = = 200200

    Test Statistic: Test Statistic:

    8 8 -- 170170

    nn = = 200200

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0-1.645

    .05

    Reject

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test SolutionSolution

    HH00: : pp = .10= .10

    HHaa: : pp < .10< .10

    = = .05.05nn = = 200200

    Test Statistic: Test Statistic:

    Zp p

    p p

    ( )

    .

    . ( . ).0

    0 01

    11200

    10

    10 1 10212

    8 8 -- 171171

    nn = = 200200

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0-1.645

    .05

    Reject

    n0 0

    200

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test SolutionSolution

    HH00: : pp = .10= .10

    HHaa: : pp < .10< .10

    = = .05.05nn = = 200200

    Test Statistic: Test Statistic:

    Zp p

    p p

    ( )

    .

    . ( . ).0

    0 01

    11200

    10

    10 1 10212

    8 8 -- 172172

    nn = = 200200

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0-1.645

    .05

    Reject Reject at Reject at = .05= .05

    n0 0

    200

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test SolutionSolution

    HH00: : pp = .10= .10

    HHaa: : pp < .10< .10

    = = .05.05nn = = 200200

    Test Statistic: Test Statistic:

    Zp p

    p p

    ( )

    .

    . ( . ).0

    0 01

    11200

    10

    10 1 10212

    8 8 -- 173173

    nn = = 200200

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0-1.645

    .05

    Reject Reject at Reject at = .05= .05

    There is evidence new There is evidence new system < 10% defectivesystem < 10% defective

    n0 0

    200

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test Thinking ChallengeThinking Challenge

    Youre an accounting Youre an accounting manager. A yearmanager. A year--end audit end audit showed showed 4%4% of transactions of transactions had errors. You implement had errors. You implement

    8 8 -- 174174

    had errors. You implement had errors. You implement new procedures. A random new procedures. A random sample of sample of 500500 transactions transactions had had 2525 errors. Has the errors. Has the proportionproportion of incorrect of incorrect transactions transactions changedchanged at the at the .05.05 levellevel? ?

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test Solution*Solution*

    HH00: :

    HHaa: :

    = = nn = =

    Test Statistic: Test Statistic:

    8 8 -- 175175

    nn = =

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test Solution*Solution*

    HH00: : pp = .04= .04

    HHaa: : pp .04.04 = = nn = =

    Test Statistic: Test Statistic:

    8 8 -- 176176

    nn = =

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test Solution*Solution*

    HH00: : pp = .04= .04

    HHaa: : pp .04.04 = = .05.05nn = = 500500

    Test Statistic: Test Statistic:

    8 8 -- 177177

    nn = = 500500

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test Solution*Solution*

    HH00: : pp = .04= .04

    HHaa: : pp .04.04 = = .05.05nn = = 500500

    Test Statistic: Test Statistic:

    8 8 -- 178178

    nn = = 500500

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test Solution*Solution*

    HH00: : pp = .04= .04

    HHaa: : pp .04.04 = = .05.05nn = = 500500

    Test Statistic: Test Statistic:

    Zp p

    p p

    ( )

    .

    . ( . ).0

    0 01

    25500

    04

    04 1 04114

    8 8 -- 179179

    nn = = 500500

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

    n0 0

    500

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test Solution*Solution*

    HH00: : pp = .04= .04

    HHaa: : pp .04.04 = = .05.05nn = = 500500

    Test Statistic: Test Statistic:

    Zp p

    p p

    ( )

    .

    . ( . ).0

    0 01

    25500

    04

    04 1 04114

    8 8 -- 180180

    nn = = 500500

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

    Do not reject at Do not reject at = .05= .05

    n0 0

    500

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    OneOne--Proportion Z Test Proportion Z Test Solution*Solution*

    HH00: : pp = .04= .04

    HHaa: : pp .04.04 = = .05.05nn = = 500500

    Test Statistic: Test Statistic:

    Zp p

    p p

    ( )

    .

    . ( . ).0

    0 01

    25500

    04

    04 1 04114

    8 8 -- 181181

    nn = = 500500

    Critical Value(s):Critical Value(s):Decision:Decision:

    Conclusion:Conclusion:

    Z0 1.96-1.96

    .025

    Reject H0 Reject H0

    .025

    Do not reject at Do not reject at = .05= .05

    There is no evidence There is no evidence proportion has proportion has changed from 4% changed from 4%

    n0 0

    500

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    One Population TestsOne Population Tests

    OnePopulation

    8 8 -- 182182

    Z Test(1 & 2tail)

    t Test(1 & 2tail)

    Z Test(1 & 2tail)

    Mean Proportion Variance

    2 Test(1 & 2tail)

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Confidence Intervals, HypothesisConfidence Intervals, HypothesisTests, and pTests, and p--valuesvalues

    All Start with Known Sampling Distribution forAll Start with Known Sampling Distribution forConfidence IntervalConfidence Interval

    Pr( > given distance from ) = Pr( > given distance from ) = Draw an interval of size around actualDraw an interval of size around actual

    X

    X 2/zX

    2/z

    8 8 -- 183183

    Draw an interval of size around actualDraw an interval of size around actual 11-- is the confidence levelis the confidence level

    PP--ValueValue Assume true mean Assume true mean Pr( > measured distance) = pPr( > measured distance) = p

    For oneFor one--sided value, no absolute valuesided value, no absolute value

    Hypothesis testHypothesis test Pick , If p < , reject the null hypothesisPick , If p < , reject the null hypothesis

    X

    X

    2/z

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    Calculating Type II Error Calculating Type II Error ProbabilitiesProbabilities

    8 8 -- 184184

    ProbabilitiesProbabilities

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    Power of TestPower of Test

    1.1. Probability of Rejecting False HProbability of Rejecting False H00 Correct DecisionCorrect Decision

    2.2. Designated 1 Designated 1 --

    8 8 -- 185185

    2.2. Designated 1 Designated 1 -- 3.3. Used in Determining Test AdequacyUsed in Determining Test Adequacy

    4.4. Affected byAffected by True Value of Population ParameterTrue Value of Population Parameter

    Significance Level Significance Level Standard Deviation & Sample Size Standard Deviation & Sample Size nn

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    RejectRejectDo NotDo NotRejectReject

    Finding PowerFinding PowerStep 1Step 1

    Hypothesis:Hypothesis:HH00: : 00 368368HH11: : 00 < 368< 368 = .05= .05

    n =n =15/15/2525

    DrawDraw

    8 8 -- 186186

    XX00 = 368= 368

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    RejectRejectDo NotDo NotRejectReject

    Finding PowerFinding PowerSteps 2 & 3Steps 2 & 3

    Hypothesis:Hypothesis:HH00: : 00 368368HH11: : 00 < 368< 368 = .05= .05

    n =n =15/15/2525

    DrawDraw

    8 8 -- 187187 XX11 = 360= 360

    XX00 = 368= 368True Situation:True Situation:11 = 360= 360

    DrawDraw

    SpecifySpecify

    11--

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    RejectRejectDo NotDo NotRejectReject

    Finding PowerFinding PowerStep 4Step 4

    Hypothesis:Hypothesis:HH00: : 00 368368HH11: : 00 < 368< 368 = .05= .05

    n =n =15/15/2525

    DrawDraw

    8 8 -- 188188 XX11 = 360= 360 363.065363.065

    XX00 = 368= 368True Situation:True Situation:11 = 360= 360

    065.363

    25

    1564.13680

    n

    ZXL

    DrawDraw

    SpecifySpecify

  • 2003 Pearson Prentice Hall 2003 Pearson Prentice Hall

    RejectRejectDo NotDo NotRejectReject

    Finding PowerFinding PowerStep 5Step 5

    Hypothesis:Hypothesis:HH00: : 00 368368HH11: : 00 < 368< 368 = .05= .05

    n =n =15/15/2525

    DrawDraw

    8 8 -- 189189 XX11 = 360= 360 363.065363.065

    XX00 = 368= 368True Situation:True Situation:11 = 360= 360 = .154= .154

    11-- =.846=.846

    DrawDraw

    SpecifySpecify

    Z TableZ Table

    065.363

    25

    1564.13680

    n

    ZXL

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    Power CurvesPower Curves

    PowerPower PowerPowerHH00: : 00 HH00: : 00

    8 8 -- 190190

    PowerPower

    Possible True Values for Possible True Values for 11 Possible True Values for Possible True Values for 11

    Possible True Values for Possible True Values for 11

    HH00: : ==00

    = 368 in = 368 in ExampleExample

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    ConclusionConclusion

    1.1. Distinguished Types of Hypotheses Distinguished Types of Hypotheses

    2.2. Described Hypothesis Testing ProcessDescribed Hypothesis Testing Process

    3.3. Explained pExplained p--Value ConceptValue Concept

    8 8 -- 191191

    3.3. Explained pExplained p--Value ConceptValue Concept

    4.4. Solved Hypothesis Testing Problems Solved Hypothesis Testing Problems Based on a Single SampleBased on a Single Sample

    5.5. Explained Power of a TestExplained Power of a Test

  • End of Chapter

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