Statistics in Statistics in PsychologyPsychology

AP PsychologyAP Psychology

Ahhhhhhhhhh! Run Ahhhhhhhhhh! Run Away!Away!

All You Need to Know All You Need to Know (for this year)(for this year)

#1: What is “statistics?”#1: What is “statistics?”#2: What is statistics used for?#2: What is statistics used for?#3: Measures of Central #3: Measures of Central

Tendency, Variability, and Tendency, Variability, and Correlation (Descriptive Correlation (Descriptive Statistics)Statistics)

#1: What is statistics?#1: What is statistics? The use of mathematics to organize, The use of mathematics to organize,

summarize, and interpret numerical datasummarize, and interpret numerical data 2 kinds:2 kinds:

Inferential Statistics (nice to know):Inferential Statistics (nice to know): Used to interpret data and draw conclusionsUsed to interpret data and draw conclusions Includes comparing data to Includes comparing data to laws of probabilitylaws of probability.. Includes Includes statistical significancestatistical significance and and hypothesis testinghypothesis testing..

Descriptive Statistics (need to know)Descriptive Statistics (need to know): : used to organize and summarize data. used to organize and summarize data. Include Include measures of central tendency (mean, median, measures of central tendency (mean, median,

mode)mode) Includes Includes rangerange (difference between high and low scores) (difference between high and low scores) Includes Includes variabilityvariability (how much scores vary from each (how much scores vary from each

other)other) Includes Includes correlationcorrelation (to what extent two variables (to what extent two variables seem to seem to

be be related) expressed as a coefficient between -1.00 and related) expressed as a coefficient between -1.00 and +1.00.+1.00.

#2: What is statistics used #2: What is statistics used for?for?

Drawing conclusions from data Drawing conclusions from data gathered fromgathered from experimental researchexperimental research: scientific method : scientific method

applied in the form of an experiment EX. applied in the form of an experiment EX. Spano’s hypnosis experiments or Spano’s hypnosis experiments or Harlow’s nurturing experiments on Harlow’s nurturing experiments on rhesus monkeys.rhesus monkeys.

descriptive/correlational researchdescriptive/correlational research: any : any form of data collection that does not form of data collection that does not follow the scientific method, such as follow the scientific method, such as case study (EX. Feral children)case study (EX. Feral children) naturalistic observation (EX. Goodall’s naturalistic observation (EX. Goodall’s

studies on chimps)studies on chimps) survey (LaPiere’s study on attitudes)survey (LaPiere’s study on attitudes)

#3: Descriptive Statistics#3: Descriptive Statistics Measures of Central TendencyMeasures of Central Tendency

Mean:Mean: average (add up scores, divide by # of scores) average (add up scores, divide by # of scores) Median: Median: the middle score in a distribution when the data the middle score in a distribution when the data

is lined up linearlyis lined up linearly Mode:Mode: most frequently occurring score most frequently occurring score Variability: How much do the scores in a data set vary Variability: How much do the scores in a data set vary

from (1) each other and (2) the mean?from (1) each other and (2) the mean? Related CalculationsRelated Calculations

Range:Range: the difference between the highest and the the difference between the highest and the lowest scoreslowest scores

Standard deviationStandard deviation:: how far is the score from the mean? how far is the score from the mean? CorrelationsCorrelations

Two variables are related to each otherTwo variables are related to each other 0 =weak, + or – 1= very strong0 =weak, + or – 1= very strong += two variables co-vary in the same direction EX. += two variables co-vary in the same direction EX.

Brushing and tooth healthBrushing and tooth health -= two variables co-vary inversely (in opposite directions) -= two variables co-vary inversely (in opposite directions)

EX. Brushing and tooth decayEX. Brushing and tooth decay

M&M Statistics Activity: M&M Statistics Activity: PrepPrep

Grab Grab youryour bag of M&M’s and a paper towel. bag of M&M’s and a paper towel. Apply hand sanitizer.Apply hand sanitizer. (We have __ bags of M&Ms and around __ (We have __ bags of M&Ms and around __

students). students). Open your spiral, write the date, and “M&Ms Open your spiral, write the date, and “M&Ms

Stats Activity.”Stats Activity.” Find a partner, preferably who has same kind Find a partner, preferably who has same kind

of M&Ms as you.of M&Ms as you. If your partner If your partner also has a bagalso has a bag of M&Ms, each of you of M&Ms, each of you

will dump out your own bag on your own paper will dump out your own bag on your own paper towel.towel.

If your partner If your partner does not have a bagdoes not have a bag of M&Ms, dump of M&Ms, dump out your M&Ms, eye ball about half the bag, and out your M&Ms, eye ball about half the bag, and place that half on your partner’s paper towel.place that half on your partner’s paper towel.

M&Ms Statistics Activity: M&Ms Statistics Activity: ProcedureProcedure

1. Count all the pieces in your pile. Record.1. Count all the pieces in your pile. Record. 1.B. Compare your total number to your partner’s. 1.B. Compare your total number to your partner’s.

If numbers are not the same, remove pieces at If numbers are not the same, remove pieces at random (and consume) from the person’s pile that random (and consume) from the person’s pile that has more pieces so that both members are left with has more pieces so that both members are left with the the exact same number as the smallest original exact same number as the smallest original total in the group.total in the group.

2. Working now with 2. Working now with only your own piecesonly your own pieces:: Classify candy by color and count each color- record in Classify candy by color and count each color- record in

descending orderdescending order Calculate the MEAN for your pieces- recordCalculate the MEAN for your pieces- record Calculate the MEDIAN for your pieces- recordCalculate the MEDIAN for your pieces- record Calculate the MODE for your pieces- recordCalculate the MODE for your pieces- record Calculate the RANGE for your pieces- recordCalculate the RANGE for your pieces- record

Repeat the above procedure for MEAN, MEADIAN, Repeat the above procedure for MEAN, MEADIAN, MODE, and RANGE for MODE, and RANGE for the entire amount of candy the entire amount of candy in your group and record.in your group and record.

ExampleExample 84 pieces total. My 84 pieces total. My

partner had 86, so we partner had 86, so we ate 2 of hers.ate 2 of hers.

My pieces:My pieces: Green:22Green:22 Blue: 18Blue: 18 Brown: 8Brown: 8 Red: 4Red: 4 Orange: 20Orange: 20 Yellow: 12Yellow: 12

Our pieces:Our pieces: Green: 45Green: 45 Blue: 35Blue: 35 Brown: 19Brown: 19 Red: 9Red: 9 Orange: 43Orange: 43 Yellow: 29Yellow: 29

Mine

Mean= 14 (ave. number of each color)

Median= 16 (descending order. Even # of colors, so add middle two scores and divide by 2)

Mode= none, b/c no repeat numbers

Range= 16 (diff. between 22 and 4)

Scores in descending order:

22, 18, 20, 12, 8, 4

Mine + Partner’s

Etc . . . .

ReflectReflect Consider:Consider: Are M&M bags similar in Are M&M bags similar in

their contents? Explain.their contents? Explain. CreateCreate: Create the premise for a : Create the premise for a

psychological study that would psychological study that would utilize statistics. Set up the utilize statistics. Set up the experiment and, in Step #3, explain experiment and, in Step #3, explain how statistics would be used.how statistics would be used.

TitleTitle: My Experimental design: My Experimental design

Steps You’ll Do Steps You’ll Do and Exampleand Example

##1-Formulate a hypothesis1-Formulate a hypothesis: There is a positive correlation between fast food consumption : There is a positive correlation between fast food consumption

and the increase of diagnosed mood disorders during the past 10 years. and the increase of diagnosed mood disorders during the past 10 years.

#2- Design the study#2- Design the study: :

Length: Length: 6 months. 6 months. Control group: Control group: 50 non-disordered individuals who will be given an 50 non-disordered individuals who will be given an

average American fast food intake. average American fast food intake. Experimental group: Experimental group: 50 non-disordered individuals 50 non-disordered individuals

who will be asked to consume an excessive amount of fast food. who will be asked to consume an excessive amount of fast food. IV: IV: amount of fast amount of fast

food consumed. food consumed. DV:DV: symptoms of mood disorder. symptoms of mood disorder. Operational DefinitionsOperational Definitions: symptoms : symptoms

of mood disorder= (1) distorted thoughts, (2) self-reported feelings of anxiety, panic of mood disorder= (1) distorted thoughts, (2) self-reported feelings of anxiety, panic

attacks, pounding heart, or dry mouth, (3) crying, wringing hands, or other physical attacks, pounding heart, or dry mouth, (3) crying, wringing hands, or other physical

signs of distress, or (4) self-report or signs of depression [lack of energy, bland facial signs of distress, or (4) self-report or signs of depression [lack of energy, bland facial

expression, lack of participation in social groups.expression, lack of participation in social groups.

#3- Consider the data:#3- Consider the data:

Symptoms of mood disorder will be rated per individual on a 1-10 scale according to Symptoms of mood disorder will be rated per individual on a 1-10 scale according to

(1) number of symptoms manifested and (2) intensity of symptoms. Mean scores from (1) number of symptoms manifested and (2) intensity of symptoms. Mean scores from

both the experimental and control groups will be calculated to compare average scores both the experimental and control groups will be calculated to compare average scores

of the two groups. Also, scatterplots of each will be made to assess correlational value of the two groups. Also, scatterplots of each will be made to assess correlational value

of these two variables and deviation from mean (Standard Deviation).of these two variables and deviation from mean (Standard Deviation).

Steps You Won’t DoSteps You Won’t Do

#4- Analyze the data #4- Analyze the data

and draw conclusionsand draw conclusions

#5- Report the findings#5- Report the findings