Factor Analysis: the Centroid Method

Abstract

We begin with a matrix or table of correlations between a set of variables. Since we are employing product-moment correlations as our starting-point, it is important that the assumptions underlying their use are met. To re-iterate briefly: ideally, the distributions of the variables should be continuous and reasonably normal (at least they should not be bimodal or markedly skewed); discontinuous variables will be discussed further in Chapter 7. Regression should be linear, and samples should be large (at least several hundred) to ensure reliability of the resulting correlations.