The comparison of occupational mortality rates

Abstract Abstract The latest study by the Registrar General of Occupational Mortality in England and Wales raises once again the problem of the choice of a suitable function for comparing the mortality experience of different groups within a population. Certain tests are proposed which should be satisfied by any acceptable index, and it is shown that the C.M.F. satisfies these tests while the S.M.R. does not. We have thus reached a somewhat curious position in this country. Theoretical considerations point to the C.M.F. as a suitable choice, yet, relying on empirical tests, it is the S.M.R. and not the C.M.F. that is employed in practice. When theory and practice appear to drift apart there is need for re-examination. Either the theory needs modification or the practice should be brought into conformity with it. But there is a third possibility. There may exist some hitherto unknown relation between them which renders the divorce more apparent than real. This possibility is explored and an approximate relation is derived. Finally the author discusses the conditions under which the two functions are approximately equal in value.