Psych FRQs: Essential Info

Type of Study: Experiment

Used to determine cause and effect between variables. Key terms: IV/DV, Control Group, Confounding Variable, Random Assignment, Placebo, Cause-effect conclusion

Type of Study: Correlational Study

Used to identify a relationship (not causation) between variables. Key terms: Positive/Negative Correlation, Scatterplot, No cause-effect

Technique (not a type of study): Survey

Used to gather self-reported attitudes or behaviors. Key terms: Wording Effect, Random Sampling, Social Desirability Bias

Type of Study: Case Study

Study one person or a small group in depth. Key terms: In-depth insight, Lacks generalizability

Type of Study: Naturalistic Observation

Observe behavior in natural setting without manipulation. Key terms: No manipulation, Descriptive only, High ecological validity

Type of Study: Longitudinal Study

Study same group over a long period. Key terms: Tracks development over time, Time-consuming

Type of Study: Cross-Sectional Study

Compare different groups at one point in time. Key terms: Snapshot comparison, Cohort effect risk

Type of Study: Meta-Analysis

Combines results of multiple studies to draw broader conclusions

Mean

The average of a data set (add all scores, divide by number of scores). Use for central tendency or effects of skew. Affected by outliers. In positive skew: mean > median.

Median

Middle value when data is ordered. Use for central tendency resistant to outliers. Best for skewed data.

Mode

Most frequently occurring score. Use when comparing modes. There may be no mode, one mode, or multiple modes.

Range

Difference between highest and lowest scores (max - min). Describes spread/variability. Very sensitive to outliers.

Standard Deviation

Measures variability around the mean. Higher SD = more spread; Lower SD = more consistency. Key for comparing data sets.

Normal Distribution

A symmetrical, bell-shaped curve where most scores fall near the mean. Use when interpreting standard deviations or percentages. 68% within 1 SD, 95% within 2 SDs, 99.7% within 3 SDs.

Positive Skew

Distribution with long tail on right (few high outliers). Mean > Median.

Negative Skew

Distribution with long tail on left (few low outliers). Mean < Median.

Statistical Significance

Results unlikely due to chance (p < .05). Shows IV had an effect. Result is reliable, not always meaningful.

Correlation Coefficient (r)

Number from -1 to +1 showing strength/direction of a relationship. Use when describing relationships. Positive r = increase/increase; Negative r = increase/decrease.

Descriptive vs. Inferential Statistics

Descriptive = summarize data; Inferential = generalize findings. Know what type is being asked in prompt.

Effect Size

Tells strength of relationship between variables. Can be large or small.

Percentile Rank

Percent of scores at or below a given score.

Informed Consent / Assent

Participants must know the purpose, risks, and voluntarily agree to participate.

Right to Withdraw

Participants may leave the study at any time without penalty.

Confidentiality

Participant data must be kept private and identities protected.

Protection from Harm

Participants must be protected from physical and psychological harm.

Limited Deception

Deception is allowed only when necessary, and participants must be debriefed afterward.

Debriefing

After the study, participants must be told the true purpose and any deception must be explained.