## Multiple choice questions

The combined effect of two variables on another is known conceptually as _______, and in statistical terms as _________

1. Mediation, an interaction effect
2. Moderation, a direct effect
3. Moderation, an interaction effect
4. Mediation, a direct effect

#### Answer: Moderation, an interaction effect

Imagine we wanted to look at the relationship between the number of hours spent practising the guitar per week and skill level. If we had reason to believe that the strength or direction of the relationship between these variables will be affected by level of enjoyment, what type of analysis should we conduct on these data?

1. Moderation analysis
2. Mediation analysis
3. Two-way repeated-measures ANOVA
4. ANCOVA

Taking mean centring for a given variable is achieved by:

1. Taking the mean of all scores (ignoring from which variable they come) and subtracting each score from it.
2. Taking each score and subtracting from it the mean of all scores (for that variable).
3. Taking each score and dividing it by the mean of all scores (for that variable).
4. Taking each score, subtracting the mean and then dividing by the standard deviation.

#### Answer: Taking each score and subtracting from it the mean of all scores (for that variable)

Why is it a good idea to centre your variables when conducting a moderation analysis?

1. It makes the data normally distributed.
2. It aids the interpretation of the indirect effect.
3. Because it reduces multicollinearity between main effects and the interaction effect.
4. It ensures the relationship between the predictor and outcome is linear.

#### Answer: Because it reduces multicollinearity between main effects and the interaction effect

Imagine we wanted to look at whether enjoyment of guitar playing influences the relationship between time spent practising and skill level. How would we know if we had a significant moderation effect?