A must if "educational measurement" interests you
I work at an educational testing company and have 150-200 books in Statistics and Psychometrics. This is one of the 10 books that I keep close to me because I use these books most. The book is just at the right level for most people in the field--not too technical, but has the relevant details. The 3rd edition is bigger and better. It includes references to several recent research articles.
