Statistics in Psychology

1. Statistics in Psychology AP Psychology Ahhhhhhhhhh! Run Away!

2. All You Need to Know (for this year) • #1: What is “statistics?” • #2: What is statistics used for? • #3: Measures of Central Tendency, Variability, and Correlation (Descriptive Statistics)

3. #1: What is statistics? • The use of mathematics to organize, summarize, and interpret numerical data • 2 kinds: • Inferential Statistics (nice to know): • Used to interpret data and draw conclusions • Includes comparing data to laws of probability. • Includes statistical significance and hypothesis testing. • Descriptive Statistics (need to know): • used to organize and summarize data. • Include measures of central tendency (mean, median, mode) • Includes range (difference between high and low scores) • Includes variability (how much scores vary from each other) • Includes correlation (to what extent two variables seem to be related) expressed as a coefficient between -1.00 and +1.00.

4. #2: What is statistics used for? • Drawing conclusions from data gathered from • experimental research: scientific method applied in the form of an experiment EX. Spano’s hypnosis experiments or Harlow’s nurturing experiments on rhesus monkeys. • descriptive/correlational research: any form of data collection that does not follow the scientific method, such as • case study (EX. Feral children) • naturalistic observation (EX. Goodall’s studies on chimps) • survey (LaPiere’s study on attitudes)

5. #3: Descriptive Statistics • Measures of Central Tendency • Mean: average (add up scores, divide by # of scores) • Median: the middle score in a distribution when the data is lined up linearly • Mode: most frequently occurring score • Variability: How much do the scores in a data set vary from (1) each other and (2) the mean? • Related Calculations • Range: the difference between the highest and the lowest scores • Standard deviation: how far is the score from the mean? • Correlations • Two variables are related to each other • 0 =weak, + or – 1= very strong • += two variables co-vary in the same direction EX. Brushing and tooth health • -= two variables co-vary inversely (in opposite directions) EX. Brushing and tooth decay

6. M&M Statistics Activity: Prep • Grab your bag of M&M’s and a paper towel. • Apply hand sanitizer. • (We have __ bags of M&Ms and around __ students). • Open your spiral, write the date, and “M&Ms Stats Activity.” • Find a partner, preferably who has same kind of M&Ms as you. • If your partner also has a bag of M&Ms, each of you will dump out your own bag on your own paper towel. • If your partner does not have a bag of M&Ms, dump out your M&Ms, eye ball about half the bag, and place that half on your partner’s paper towel.

7. M&Ms Statistics Activity: Procedure • 1. Count all the pieces in your pile. Record. • 1.B. Compare your total number to your partner’s. If numbers are not the same, remove pieces at random (and consume) from the person’s pile that has more pieces so that both members are left with the exact same number as the smallest original total in the group. • 2. Working now with only your own pieces: • Classify candy by color and count each color- record in descending order • Calculate the MEAN for your pieces- record • Calculate the MEDIAN for your pieces- record • Calculate the MODE for your pieces- record • Calculate the RANGE for your pieces- record • Repeat the above procedure for MEAN, MEADIAN, MODE, and RANGE for the entire amount of candy in your group and record.

8. Example • 84 pieces total. My partner had 86, so we ate 2 of hers. • My pieces: • Green:22 • Blue: 18 • Brown: 8 • Red: 4 • Orange: 20 • Yellow: 12 • Our pieces: • Green: 45 • Blue: 35 • Brown: 19 • Red: 9 • Orange: 43 • Yellow: 29 Scores in descending order: 22, 18, 20, 12, 8, 4 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) Mine + Partner’s Etc . . . .

9. Reflect • Consider: Are M&M bags similar in their contents? Explain. • Create: Create the premise for a psychological study that would utilize statistics. Set up the experiment and, in Step #3, explain how statistics would be used. • Title: My Experimental design

10. Steps You’ll Do and Example #1-Formulate a hypothesis: There is a positive correlation between fast food consumption and the increase of diagnosed mood disorders during the past 10 years. #2- Design the study: Length: 6 months. Control group: 50 non-disordered individuals who will be given an average American fast food intake. Experimental group: 50 non-disordered individuals who will be asked to consume an excessive amount of fast food. IV: amount of fast food consumed. DV: symptoms of mood disorder. Operational Definitions: symptoms 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 signs of distress, or (4) self-report or signs of depression [lack of energy, bland facial expression, lack of participation in social groups. #3- Consider the data: 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 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 these two variables and deviation from mean (Standard Deviation).

11. Steps You Won’t Do #4- Analyze the data and draw conclusions #5- Report the findings