1. CHAPTER 2: PSYCHOLOGICAL RESEARCH METHODS AND STATISTICS

2. SAMPLES Def: a relatively small group out of the total population
Must be representative
2 ways to “ensure”:
Random sample
Stratified sample: subgroups in pop. are represented proportionately

3. METHODS OF RESEARCH

4. NATURALISTIC OBSERVATION
Def: psychologist observes subjects in their natural setting without interfering

5. CASE STUDIES
Def: an intensive investigation of one or more participants
Does not prove or disprove
Can not be generalized
Used to generate hypotheses

6. SURVEYS
Def: info is obtained by asking many individuals a fixed set of questions
Interviews, questionnaires

7. LONGITUDINAL STUDIES
Def: data is collected about a group of participants over a number of years to assess how certain characteristics change or remain the same during development
Time consuming
Too many variables

8. CROSS-SECTIONAL STUDIES
Def: data is collected from groups of participants of different ages and compared so conclusions can be drawn about differences due to age

9. CORRELATION
Def: the measure of a relationship between 2 variables or set of data
Does NOT show cause
Positive correlation: variables move in same direction
Negative correlation: variables move in opposing directions

10. EXPERIMENTS Enables researcher to control the situation
Hypothesis: educated guess
Variable: any factor capable of change (independent, dependent)
Experimental and control group
Results must be replicated to be accepted

11. ETHICS
Def: methods of conduct; standards for proper and responsible behavior
Animal testing is the main concern today

12. SECTION 2: PROBLEMS AND SOLUTIONS IN RESEARCH

13. SELF-FULFILLING PROPHECY
Def: when a researcher’s expectations influence their behavior and thereby influence the participant’s behavior
Any conscious/unconscious cue could change results

14. AVOIDING SELF-FULFILLING PROPHECY
Single-blind experiment: participants are unaware of which participants received treatment
Double-blind experiment: neither experimenter nor participants know who received treatment

15. PLACEBO EFFECT
Def: a change in a participant’s illness or behavior that results from a belief that the treatment will have an effect, rather than the actual treatment

16. SECTION 3: STATISTICAL EVALUATION
Statistics can lie. In order to avoid that, you must collect meaningful data and evaluate it correctly

17. STATISTICS
Def: branch of math concerned with summarizing and making meaningful inferences from collections of data

18. DESCRIPTIVE STATISTICS
Def: the listing and summarizing of data in a practical and efficient way

19. DISTRIBUTIONS OF DATA
Frequency distribution: arrangement of data that indicates how often a particular score or observation occurs
Histogram: graphical representation showing a visual impression of the distribution of data

20. DISTRIBUTIONS CONTINUED
Frequency polygon/curve: line graph; can show more than one set of data
Normal curve: graph shaped like a symmetrical, bell- shaped curve; shows normal distribution

21. MEASURES OF CENTRAL TENDENCY
Central tendency: a number that describes something about the average score of distribution
Mean: average; most used measure
Median: middle score
Mode: most frequent score
Bimodal: distributions with 2 modes

22. MEASURES OF VARIANCE Variance: measure of difference, or spread Range
Standard of deviation: describes an average distance of every score from the mean; most widely used measure of variance

23. CORRELATION COEFFICIENTS
Def: describes the direction and strength of the relationship between 2 sets of variables
Take a value between and 1
Scatterplot: graph of scores representing the direction of the relationship

24. INFERENTIAL STATISTICS
Def: numerical methods used to determine whether research data support a hypothesis or whether results were due to chance

25. STATISTICAL SIGNIFICANCE
When probability of a result is 1-5% it is said to be statistically significant
Represented as “p” value
Tells us likelihood