“…As described in Chapter I, statistical analyses utilizing concomitant information have been used in fixed-sample-size experimentation for the multivariate case (see, for example, Rao, 1966) , as well as for the univariate case (see, for example, Cochran, 1957); and, as noted therein, at least one purpose for the utilization of concomitant information is to remove the effects of disturbing variables in observational studies. With this purpose in mind, Roseberry (1965), Cox and Roseberry (1966), and Sampson (1968) where X = a" Z a.…”