This paper describes a method for estimating the risk from a disease over a
set of contiguous geographical, regions, when data on a potentially import
ant covariate, such as race, are not available. Conditions under which the
extra margin can be recovered are suggested. An application to prostate can
cer mortality among the non-white population in the counties of the U.S.A.
is discussed. Copyright (C) 2000 John Wiley & Sons, Ltd.