I am conducting a mixed design ANOVA test using ezANOVA. I ran two different tests as follows:
Test1: within subject variable w, between subject variables age and x1.
Test2: within subject variable w, between subject variables age and x2.
Both tests are on the same data and same dependent variable (but I built two separate models), all independent variables are categorical.
But the output shows that, in Test1, the main effect of age is not significant, but in Test2 it is significant. My question is if this can happen or I am doing something wrong? In both tests, interaction between age and x1/x2 are not significant.