Unit 2 Research Methods: Thinking Critically with Psychological Science

1. Unit 2 Research Methods: Thinking Critically with Psychological Science

2. I. The Need for Psychological Science

3. I. The Need for Psychological Science A. Hindsight bias B. Overconfidence

4. 98% Certainty • The area of the US in square miles? • The population of Australia 2007? • American battle deaths in Spanish-American War? • Female psychiatrists in the US in 2005? • Operating nuclear plants worldwide in 2007?

5. 98% Certainty • Area of US: • Australian pop.: • Battle deaths: • Female psychiatrists: • Nuclear plants: 3.6 million sq. miles 20.4 million 385 13,079 435

6. I. The Need for Psychological Science A. Hindsight bias B. Overconfidence C. Scientific attitude 1. Curiosity 2. Skepticism 3. Humility 4. Critical thinking

7. II. How Do Psychologists Ask and Answer Questions?

8. II. Asking & Answering Questions A. The scientific method 1. Basic principles a. Theories b. Hypotheses c. Operational definitions d. Replication

9. Theory • Explanation using a set of principles that organizes observations and predicts behavior or events • Not just a guess • Based on research and tested information • Organize isolated facts = simplify Ex. “Sleep improves memory”

10. Hypothesis • Testable prediction implied by a theory • Not an “educated guess” • A testable question based on a theory • Has testable predictions Ex. “When sleep deprived, people remember less from the day before.”

11. Operational Definition • Statement of the exact procedures (operations) used in a research study • Leaves nothing to subjectivity • Explains specifically Ex. “Sleep deprived = X hours or less” Let’s practice – create an operational definitionn for the following: Happiness Popularity Good music Intelligence

12. Replication • Repeating the study, usually with different participants to see if the finding extend to others • To be a valid finding, it must be replicable

13. Scientific Method Don’t forget your operational definitions so it can be repeated

14. II. Asking & Answering Questions A. The scientific method 1. Basic principles 2. Descriptive techniques a. Case studies (1) Problem? Can be misleading (2) Why used? Provides study opportunitiesnot otherwise available Phineas Gage 1823-1860

15. II. Asking & Answering Questions A. The scientific method 1. Basic principles 2. Descriptive techniques a. Case studies b.Surveys (1) Wording effects 72% interested in “plants & trees” 39% interested in “botany”

16. 1. Is the Mississippi River longer or shorter than 500 miles? 2. How many miles long is it?

17. 1. Is the Mississippi River longer or shorter than 3000 miles? 2. How many miles long is it?

18. II. Asking & Answering Questions A. The scientific method 1. Basic principles 2. Descriptive techniques a. Case studies • b. Surveys • (1) Wording effects (2) Sampling (a) Populations • All those in group being studied (b) Random samples

21. II. Asking & Answering Questions A. The scientific method 1. Basic principles 2. Descriptive techniques a. Case studies • b. Surveys c. Naturalistic observation

22. II. Asking & Answering Questions A. The scientific method 1. Basic principles 2. Descriptive techniques 3. Correlation and prediction a. Types b. Scatterplots

23. II. Asking & Answering Questions Negative Correlation Positive Correlation

24. II. Asking & Answering Questions No Correlation

25. II. Asking & Answering Questions 3. Correlation and prediction b. Scatterplots c. Correlation coefficients (useful at .2 and up/higher numbers = greater predictability

26. II. Asking & Answering Questions 3. Correlation & prediction c. Correlation coefficients d. Correlation does not establish cause & effect!!!!!!! There is a correlation between TV watching and GPA What do we know about cause and effect?

30. II. Asking & Answering Questions 3. Correlation & prediction d. Correlation does not establish cause & effect!!!!!!! • e. Illusory correlation • perception of a relationship where none exists • Ex: Getting wet and chilled causes people to “catch a cold” • Ex: Infertile couples are more likely to conceive after they adopt • Sometimes we forget, random coincidences are really are just random – we deceive ourselves by seeing a connection that isn’t there

31. II. Asking & Answering Questions 3. Correlation & prediction d. Correlation does not establish cause & effect!!!!!!! e. Illusory correlation f. Random may not seem random

32. II. Asking & Answering Questions A. The scientific method 1. Basic principles 2. Descriptive techniques 3. Correlation and prediction 4. Experimentation and causation

33. Experimentation Purpose of an expt: General hypothesis: food affects learning Specific (operationalized) hypothesis: students who eat an oatmeal raisin cookie before class each day will have higher average scores on the semester final than students who don’t eat a cookie.

34. Eating cookies before class each day will lead to higher average scores. Variables: Independent (IV) Controlled by experimenter The “cause” variable Dependent (DV) Predicted by experimenter The “effect” variable

35. Eating cookies before class each day will lead to higher average scores. What if kids get cookies and A’s? Groups (conditions): to establish different levels of the IV Experimental group Exposed to IV Get cookie Control group Not exposed to IV No cookie

36. IV DV Eating cookies before class each day will lead to higher average scores. Confounding Variables Environmental Expt. Gp. Cookie 95% Expectations Cntrl. Gp. No Cookie 82% Individual differences

37. Random Sampling To select participants from population Allows you generalize results Random Assignment To divide participants into groups Controls confounding variables

38. IV DV Eating cookies before class each day will lead to higher average scores. Expt. Gp. Cookie 95% Cntrl. Gp. No Cookie 82% 85% 93%

39. Statistical Significance p value likelihood a result is caused by chance can be no greater than 5% p ≤ .05

40. IV DV Replication Non-replicated results are preliminary. Linus Pauling (1970). Vitamin C prevents colds. Expt. Gp. 45% Fewer colds Expt. Gp. Vit C Cntrl. Gp. Placebo

41. Experimental Design Terms • Hypothesis • Operational definitions • Participant selection • IV & DV • Experimental & control groups • Confounding variables • Random assignment • Placebo control • Double blind procedure • Statistical significance (p value) • Replication

42. Quasi-experiments • Men are better drivers than women. • Cigarette smoking causes lung cancer.

43. Practice with IV & DV • Exposing children to public television improves their reading. • You’ll have fewer problems in the future if you get psychotherapy. • Getting complements makes people work harder on an assembly line.

44. Students are more likely to smile for their senior pictures if they have a friendly photographer. IV? DV?

46. III. Statistical Reasoning

47. III. Statistical Reasoning A. Describing data 0. Frequency distributions 1. Bar graph (histogram) 2. Line graph (frequency polygon)

48. III. Statistical Reasoning A. Describing data 0. Frequency distributions 1. Central tendency 4 3 5 4 4 a. Mode --Most common=4 b. Mean --Arithmetic avg=20/5=4 c. Median --Middle score=4

49. Nolan Ryan $1500 Billy Williams $8 Luis Aparicio $5 Harmon Killebrew $5 Orlando Cepeda $3.50 Maury Wills $3.50 Jim Bunning $3 Tony Conigliaro $3 Tony Oliva $3 Lou Pinella $3 Mickey Lolich $2.50 Elston Howard $2.25 Jim Bouton $2 Rocky Colavito $2 Boog Powell $2 Luis Tiant $2 Tim McCarver $1.75 Tug McGraw $1.75 Joe Torre $1.5 Rusty Staub $1.25 Curt Flood $1 Central Tendency 1968 TOPPS Baseball Cards With Ryan: Median=$2.50 Mean=$74.14 Without Ryan: Median=$2.38 Mean=$2.85