Stats in Psych Exam 3 review

What is a repeated-measures design?

A design where the same participants are used in all treatment conditions.

What is an advantage of repeated-measures design?

Reduced individual differences

What is a disadvantage of repeated-measures design?

Order effects can influence the second treatment

What does the D score represent in a paired t-test?

The difference between two related scores for the same individual.

What is the D score formula?

D=X2-X1

Why does using D scores reduce error?

Removes individual differences, reduces variance and standard error

Which of the following is NOT an assumption for a repeated measures t-test?

Nominal dependent variable

What is the purpose of ANOVA?

To test for differences among more than two group means while controlling Type 1 error.

Why not use multiple t-tests instead of ANOVA?

Increases the risk of Type 1 error.

What is the F- ratio formula?

F= variance between groups/variance within groups (F=BT var/WTvar)

What is a “factor” in ANOVA?

Independent variable

If F(3,116)=6.89 AND p<.001, what does this indicate?

Overall significant difference

What are “levels” of a factor?

Specific groups or conditions of the IV

What would you use to most accurately compare means of 4 groups?

One-Way ANOVA

What are Post HOC tests used for?

where the significant difference is; determine which specific group differences are significant after a significant ANOVA result

What condition increases within-group variance?

Random error

What does n2 (eta squared) measure?

effect size in ANOVA

What is a two-way ANOVA?

ANOVA with two independent variables.

What is a main effect in ANOVA? (simple)

Effect of one IV

What is an interaction effect in a Two-way ANOVA? (simple)

combined effect of both IVs

What type of ANOVA would you use for a study that examines gender (male/female) and study method (solo/group) on test scores?

2×2 factorial ANOVA

Factorial designs can test for…

main effects AND interactions

What is an interaction effect?

When the effect of one IV depends on the level of the other IV

Why are interactions important in behavioral research?

They reveal how variables jointly influence outcomes in ways main effects alone can’t show

How should two way ANOVA results be reported?

F(df,df)=f ratio, p=, n2=