I am not a hard core statistician but have tried reading some books and understand ing the subject. I am working on a project where I need to use "Heckman Selection Sample". My problem is I am just not able to understand how this model works.
If I get some illustration say in Excel, it would be very useful for me to understand this. I have Googled but didn't come across a site where it is explained step-by-step and how it is to be interpreted.
Take a look at Limited Dependent Variables chapter of Peter Kennedy's A Guide To Econometrics. This is the clearest explanation I know of. The graphical intuition is presented first, there are some simple linear equations in the General Notes, and even more details in the Technical Notes. In particular, this will help you decide whether you need a tobit or the Heckman sample selection model, of which the tobit is a special case.
If you still can't figure out which boat you're in, it would help if you provided more details about the particulars of your problem and the software you might have access to. Excel is probably not the best tool for this, though it might be doable.
