I have learned the basic method of cross-validation, but I have a question. Before cross-validation, how to build a logistic regression model fist? I mean that should I use the complete data set to build logistic regression model(not split data to training set and validation set), and then use the complete data set for K Fold cross-validation?
For example: My data set is named
mydata, and then use the complete data set to filter variables and build logistic regression model, finally, use the model and complete data set to perform K-fold cross-validation, is this process correct?