ABSTRACT
Psychometrics is defined in Chambers Twentieth Century Dictionary as the ‘branch of psychology dealing with measurable factors’, but also as the ‘occult power of defining the properties of things by mere contact’. While it is the first of these definitions that we shall be dealing with in this book, there have been times in recent years when the second might have seemed more accurate as a description of current practice, particularly in debates about intelligence. It is impossible to consider the development of modern-day psychometrics without looking at the substantial influence of the intelligence testing movement in the late nineteenth and early twentieth centuries. However, the origins of the subject go back long before then.
