Hi there,

I am trying to conduct a moderation analysis (Model1) using PROCESS for SPSS by Hayes.

I have an independent variable containing of three groups: 1 control group (1) + 2 test groups (2 and 3). I want to compare each test group with the control group, i.e. 1 vs 2 and 1 vs. 3. Can this be done using the multicategorial option?

I am uncertain whether the dummy variables created by PROCESS will take the control group AND the other test group as a reference category or just the control group.

Coding of categorical X variable for analysis:

Stimulus X1 X2

1,000 ,000 ,000

2,000 1,000 ,000

3,000 ,000 1,000

So can I conduct one analysis using this multicategorial option or do I have to create dummy variables manually and conduct two separate analyses?

Many thanks.