She found, however, that the instruments were used in isolation--rarely, if ever, were two or more used in the same study to establish criterion validity--and recommends large, interdisciplinary, multivariate studies
One is tempted to attribute the upward trends in the early 1970s to ESP, but multivariate studies that adjust for confounding influences generally report no significant changes in this utilization measure (Ginsburg, 1976; Coelen, Mennemeyer, and Fidder, 1986).
In a review of the empirical work, Steinwald and Sloan (1981) found that descriptive studies of the effects of ESP and other regulatory programs showed larger reductions in hospital costs than did multivariate studies adjusting for confounding influences such as CON, section 1122 programs, utilization review activities, and other factors.
Multivariate studies showed smaller changes in profit margins than descriptive studies, because multivariate studies incorporated efforts to adjust for factors other than ESP that influenced hospital behavior.
Multivariate studies showed a relatively strong impact of ESP on wages and employment.
With the exception of admission patterns, multivariate studies generally found smaller changes in utilization than noted above in our trend analyses (Figures 7-9).
Generally, multivariate studies showed smaller changes in economic factors and about the same size changes in utilization as our trend analyses.