BAPSY - Bachelor of Arts in Psychology Bachelor of Arts in Psychology: Methodical & Stats Analysis 1

Question 1

A researcher sets alpha at 0.05 and fails to reject a null hypothesis that is actually false. What type of error has occurred?

Accepted Answer

Type II error

Answer

A Type II error (beta error) occurs when a researcher fails to reject a false null hypothesis — a 'miss.' A Type I error is the opposite: rejecting a true null hypothesis.

Question 2

A multiple regression model yields R² = 0.64. A researcher adds a second predictor and R² increases to 0.65. What should the researcher most likely conclude?

Accepted Answer

The increase in R² is likely due to chance and the predictor adds little value

Answer

An R² increase of only 0.01 (1%) is trivially small. Researchers should examine adjusted R² and the predictor's significance before concluding the new variable meaningfully improves the model.

Question 3

Cohen's d is calculated as 0.20 for a study comparing two group means. How is this effect size conventionally interpreted?

Accepted Answer

Small effect

Answer

By Cohen's conventions, d = 0.20 is a small effect, d = 0.50 is medium, and d = 0.80 or above is large. A small effect can still be meaningful depending on the research context.

Question 4

A psychologist measures anxiety levels in the same group of participants before therapy, after 4 weeks, and after 8 weeks. Which statistical test is most appropriate?

Accepted Answer

Repeated-measures ANOVA

Answer

Repeated-measures ANOVA is used when the same participants are measured at three or more time points, accounting for within-subject correlation. An independent-samples t-test or between-subjects ANOVA would be inappropriate because the groups are not independent.

Question 5

A scale measuring depression produces very similar scores when administered to the same participants two weeks apart. This scale demonstrates high:

Accepted Answer

Test-retest reliability

Answer

Test-retest reliability refers to the consistency of scores over time when the measured construct has not changed. Validity addresses whether the scale measures what it is intended to measure — a separate property.

BAPSY - Bachelor of Arts in Psychology Practice Test

BAPSY - Bachelor of Arts in Psychology Practice Test

BAPSY - Bachelor of Arts in Psychology Bachelor of Arts in Psychology: Methodical & Stats Analysis 1