Psychology Stats

Why is ANOVA used instead of multiple t-tests?

ANOVA compares 3 or more means simultaneously while controlling familywise Type I error.

What is familywise error?

The increased probability of making at least one Type I error when conducting multiple statistical tests.

What is a factor in ANOVA?

The independent variable being studied.

What are levels in ANOVA?

The different groups or conditions within a factor.

What is the null hypothesis for a one-way ANOVA?

All population means are equal.

What does a significant F-ratio indicate?

It indicates at least one group mean differs from the others.

Why is ANOVA called an omnibus test?

It tells us whether any differences exist but not which groups differ.

Follow-Up Tests

Front: Why are follow-up tests conducted after a significant ANOVA?
Back: To determine which specific means differ.

What is the purpose of the Bonferroni procedure?

To reduce the risk of Type I error when making multiple comparisons.

What are linear contrasts used for?

To test specific predicted differences among means.

What does omega-squared (ω²) measure?

The proportion of variance explained by the treatment.

When is a repeated measures ANOVA used?

When the same participants are tested in all conditions.

What is a major advantage of repeated measures ANOVA?

It controls for individual differences and increases statistical power.

What is a main effect?

The effect of one independent variable averaged across levels of other variables.

What is an interaction effect?

When the effect of one independent variable depends on the level of another independent variable.

What usually indicates an interaction on a graph?

Non-parallel or crossing lines.