I am testing the effectiveness of a treatment on accuracy of decisions. I believe that the treatment will help people with low iq make more accurate decisions, and for people with high iq it won't make a difference because their decision making is already optimised.
What i do is i split the sample in high and low iq. Then i compare accuracy between control and treatment within low iq and control and treatment within high iq.
In this scenario, is my model
- testing the moderating effect of treatment on the relationship between iq and accuracy, or
- testing the moderating effect of iq on the relationship between control/treatment and accuracy?