- The purpose is similar to One-way ANOVA, but now we have two factors.
- Example: Is the amount of weekly physical activity of college students different in three states for male and female?
- Two factors: state, gender.

- Main effect
- Will the state influence the amount?
- Will gender influence the amount?

- Interaction
- Is the influence of state the same for male and female?

- If any lines cross each other, then you
**have**an interaction. - If the lines are all fairly parallel to each other, then you
**do not have**an interaction. - If the lines aren't parallel but don't cross each other either, then you
**might have**an interaction.

- Need independent SRSs
- Population should be Normal with the same standard deviation
- Largest std. < 2 * smallest std.