I'm trying to calculate logistic regression in SPSS, in order to indentify predictors to successful treatment group.

so my dependent variable is: treatment success (categorical variable)

and my covariates are:

1. age (continuous variable)

2. anxiety score (continuous variable)

3. depression scores (continuous variable

4. age group (categorical variable)

My questions are:

1. Should I run the test several time with each of this covariates by itself. Or should I run the test with all these covariates together

2. do I need to specify in the spss logistic regression dialog box that covariate 4, is a categorical variable?

Thanks a lot.