Key points are not available for this paper at this time.
Jeffrey H. Silber, Paul R. Rosenbaum, Richard N. Ross, Comparing the Contributions of Groups of Predictors: Which Outcomes Vary With Hospital Rather Than Patient Characteristics, Journal of the American Statistical Association, Vol. 90, No. 429 (Mar., 1995), pp. 7-18
Silber et al. (Wed,) studied this question.