How can adding a 2nd IV make the 1st IV significant?
I am looking at the prediction of relapse by gender. In a hierarchical log regression, with gender entered in first block, it is significant. When anxiety is entered in second block, both anxiety and gender are insignificant. Interaction terms are also insignificant. What does this mean? It is clearly not a moderator or mediator effect because anxiety does not predict relapse (even when entered before gender). Is this simply an effect of multicollinearity between gender and anxiety? Because gender is more strongly related to anxiety than to relapse?