Fairly novice in statistics, so this will surely have a simple explanation. I ran bivariate analyses to check for normality of a series of variables and also to test the relationship of each with two outcome variables (one binary the other continuous). In the bivariate analyses (using either linear or logistic regression) none of the variables appear to be related to the outcome variables. However, when I ran the analyses including multiple variables in a GLM and GLMZ model, I did get significant results for some of the variables and good model fit statistics. How should I interpret this?