I have a question regarding binary logistic regression. My DV is dichotomous (0=no, 1=yes), and I have 9 predictor variables (dummy-coded & scale). If I do for each predictor one regression analysis, some of them are significant. But as soon as I enter one predictor with other predictors, they loose their significance levels. My question: WHY?? I now that they depend on each other, but I really do not get why this happens.
And my second question: Is it ok to run separate logistic regression for the same DV?
THANKS FOR ANSWERS :-)