THE RELATIONSHIP AMONG SUMS OF SQUARES, CORRELATION-COEFFICIENTS, ANDSUPPRESSION

We examine the relationship between the extra sum of squares SSR(x(2)/ x(1)), the regression sum of squares SSR(x(2)), and the correlation co efficients r(y1), r(y2), and r(12). From this we develop a necessary a nd sufficient condition for suppression in terms of the correlation co efficients, We use this to investigate the conditions under which supp ression can occur algebraically and graphically. We believe that expre ssing suppression in terms of correlation coefficients may help studen ts and applied researchers to identify cases of suppression and to und erstand when suppression can occur.