Although I have used this text as a reference (vs. reading it all the way through, or for a class) I have found myself returning to it often. In fact, I purchased it only because I had started to wear out the copy I had borrowed from a friend...and she was missing it because she used it frequently, too. The best aspect of this text is the way the authors use examples relevant to clinical research for nearly every statistical decision. No more extrapolating from educational research, medical research...I don't usually have that much imagination! Good book.