Susan (University of Cambridge, UK) Golombok & John Rust 
Modern Psychometrics [PDF ebook] 

The edition of this classic text has been completely revised and updated, taking into account recent developments in the field of psychometrics. Part 1 of
Modern Psychometrics outlines the background, history and controversies surrounding psychological testing. Part 2 provides a practical guide for developing a psychometric test.
Modern Psychometrics forms the ideal companion for those studying for the British Psychological Society”s Certificates of Competence in Testing