Testing a hypothesis and hypothesis generation

I like this podcast. It discusses some recent findings about genes possibly relating to Alzheimer's Disease. In it, the guest speaks of not having a hypothesis going into the study. Then the host (or another guest) raised the question of conducting a study without a pre-defined hypothesis. The keyword was "hypothesis generation." I'm happy this was brought up on NPR (although this wasn't the point of the show). I might use it as an example in class some day.