# Categorical predictors and moderation (L8) Flashcards

1
Q

What are dummy variables?

A

A way of recording categorical variables with 2 + categories into a series of dichotomous variables (eg. 0 or 1).

2
Q

How do you make dummy variables?

A

1) Count groups you want to recode - 1
2) Create as many new variables as calculated in step 1
3) Choose one group as a baseline (the group all others with be compared to)
4) Assign that baseline to 0
5) 1st dummy variable = 1, all others 0
6) 2nd dummy variable = 1, all others 0
7) Repeat until all variables have been tested.

3
Q

What does the linear model for dummy variables look like?

A

One line connecting all the means. Intercept = mean of 0 coded group; â€˜bâ€™/gradient = difference between means of categories.

4
Q

What is moderation?

A

The relationship between variables changes as a function of a third variable.

5
Q

What is a moderator variable?

A

Variable that changes the size and/or direction of the relationship between 2 other variables.

6
Q

What is interaction?

A

Predictor x moderator

If significant as a predictor you have a significant moderation effect.

7
Q

What are simple slope analysis?

A

Graph showing the relationship at varying levels of moderator.