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1The Nature of Probability and Statistics1.1Descriptive and Inferential StatisticsSlide 1Copyright 2012 The McGraw-Hill Companies, Inc. 1-1Descriptive and Inferential Statistics1-2Variables and Types of Data1-3Data Collection and Sampling Techniques1-4Observational and Experimental Studies1-5Uses and Misuses of Statistics1-6Computers and Calculators (Excel)

Mean hours of WI girl babies daily sleeping hours.Does my new product last longer than the old one?Statistical study conceptThis chapter mainly introduces new concepts and terminology, not much calculations.OutlineC H A P T E R

Are We Improving Our Diet?

YES or NO? How would we show that statistically?2 2Probability is interested in the analytical calculation of probability E.g., Rolling two dies. Probability of getting one even number and the other multiple of 3? Statistics collect, organize, summarize, analyze, and draw conclusions about the population using data (or sample).

N= 30n=3

Probability vs. Statistics 3Ch. 24Prof. Barlow (UCB)Probability does not exist!Time is discrete!What do we mean byProb ( on a die) = 1/6Prob ( living creature on Mars) = 1/2Bayesian vs. FrequentistProf. BarlowProf. Ross and Prof. WolffProbability Concept: What is probability?5Professors at UCB Barlow Wolff Ross

Statistics concept: Sampling Study6population (true) mean (m)population (true) variance (s2)Population (N)X1, X2, X3, , XnSamplingOne sample (size n)Estimation of m or s2.

1-1 Descriptive and Inferential StatisticsTerminology Variable: a characteristic or attribute Data value = datum: value a variable took Data=data set: set of datum Random experiment: experiment when... Random variable: variable whose value ... E.g., Name of stat student = {John, Kim} Height of stat student = {58, 61}7Descriptive statistics What to show (mmm, ISU) How to show

Inferential statistics Estimation of mean/var Statistical Test Regression

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x1, x2, x3UWM heightsInferential StatisticsThe difference of mean heights of UWM students and Marquette students. (Estimation)Support rate of Democrats in Wisconsin is 453%. (Estimation)My medicine works faster than yours. (Test)Smoking affects expected life? (Test)I love you. (Test!)Relationship between humidity and death rate. (Regression) We need a sampling study for these.991-2 Variables and Types of DataDataQualitative*Categorical(gender, residency county)QuantitativeNumerical, Can be rankedDiscreteCountable5, 29, 8000, etc.ContinuousCan be decimals2.59, 312.1, etc.10(*can/cannot be ranked)Recorded Values and BoundariesVariableRecorded Value(value) Boundaries*Length15 centimeters (cm)Temperature86 Fahrenheit (F)Time0.43 second (sec)Mass1.6 grams (g)14.5-15.5 cm85.5-86.5 F0.425-0.435 sec1.55-1.65 g11(of continuous variables)* Conventionally this means [A,B)Levels of MeasurementNominal categorical (names)Ordinal nominal, plus can be ranked (order)Interval ordinal, plus intervals are consistent Ratio interval, plus ratios are consistent, true zero12Determine the measurement level.VariableNominalOrdinalIntervalRatioLevelHair ColorYesNoNominalZip CodeYesNoNominalLetterGradeYesYesNoOrdinalACT ScoreYesYesYesNoIntervalHeightYesYesYesYesRatioAgeYesYesYesYesRatioTemperature(F)YesYesYesNoInterval1314Bluman Chapter 1

The measurement levelGroupRankingDifferenceZero1-3 Data Collection & Sampling TechData collection methods Telephonecheap, candid / tone of voice, biased sample Mailed questionnairecheap, anonymous / low resp rate, inapp. answers Personal interviewexpensive, biased interviewer Direct observation15Or perform experiments.Some Sampling TechniquesRandom random number generatorSystematic every kth subjectStratified divide population into groups and takes samples from each group.Cluster divide population into groups select one group, and study it thoroughly.Convenient mall surveys161-4 Observational and Experimental StudiesObservational study: the researcher merely observes what happens.Experimental study: the researcher manipulates the independent (explanatory) variables and checks their influences on the dependent (outcome) variable.

A confounding variable influences the dependent variable but cannot be separated from the independent variable.17

1-5 Uses and Misuses of StatisticsSuspect SamplesIs the sample large enough?Is the sample representative of the population?Family member? Volunteers? Men? With cell phones? Classroom-convenience sampling?Ambiguous AveragesWhat particular measure of average was used and why?18Changing the SubjectAre different values used to represent the same data?Detached StatisticsOne third fewer calories.than what?Implied ConnectionsStudies suggest that some people may understand what this statement means.19Misleading GraphsAre the scales for the x-axis and y-axis appropriate for the data?Faulty Survey QuestionsDo you feel that statistics teachers should be paid higher salaries?Do you favor increasing tuition so that colleges can pay statistics teachers higher salaries?20

1-6 Computers and CalculatorsMicrosoft ExcelMicrosoft Excel with MegaStatTI-83/84MinitabSAS SPSS21211-6 Computers and CalculatorsMicrosoft Excel Statistics Menu =average(.)Home > Auto Sum > Home > Auto Sum > More Functions > StatisticalFormula > Insert function >

If needed, insert Add-Ins: File > Options > Add-Ins > Excel Add-Ins > Analysis Tool Pack (p. 24)

2222Yuna Kim Gold medalist in Vancouver 2010 Winter Olympicshttps://www.youtube.com/watch?v=6uLhN1jH6uo2323