Variable reduction technique for Logistic Regression

Variable reduction and Binning using WOE and IV 

It is a beautiful method of variable reduction for a Logistic Regression even before modeling starts. It helps you do a mathematically optimized binning of variables that would help you segregate 1 and 0 best. Interested ? ... then go ahead !
it is also one of most favorite question of interviewers ... so be little more attentive.