I am fitting a stepwise logistic regression on a set of data in SPSS. In the procedure, I am fitting my model to a random subset that is approx. 60% of the total sample, which is about 330 cases.
What I find interesting is that every time I re-sample my data, I am getting different variables popping in and out in the final model. A few predictors are always present in the final model, but others pop in and out depending on the sample.
My question is this. What is the best way to handle this? I was hoping to see the convergence of predictor variables, but that isn't the case. Some models make much more intuitive sense from an operational view (and would be easier to explain to the decision makers), and others fit the data slightly better.
In short, since variables are shuffling around, how would you recommend dealing with my situation?
Many thanks in advance.