ABSTRACT
This chapter argues that despite the mathematical rigour of psychometrics, so rigorous that in fact many psychologists have been forced or have preferred to ignore the work, psychometric measurement is far different from measurement in the natural sciences. There is a genuine and well-founded consensus about this claim among psychologists who understand factor analysis. It was the hope of psychometrics that well- defined factors could provide the basis of a quantified psychology, since it is clear that simple-structure factor analysis can reveal important fundamental variables within the matrix to which it is applied. The survey and examination of psychometric methods and of what has been found in psycho- metrics up to the present date, actually demonstrated two important points. Psychometric personality theory, especially that of Eysenck and Cattell particularly the latter, does not fall into this error. These are both examples of trait theory but ones where the traits are clearly stated and investigators are provided with clear measuring instruments.
