The accuracy of occupational vital statistics.

Statistics of mortality and morbidity in different occupational groups are essential for the effective practice of industrial medicine in the major industries. For coal-mining in 1950, the Registrar General (1954) reported a standardized mortality ratio for " hewers and getters ", i.e., coalface workers, of 154; and the Ministry of Pensions and National Insurance (1955) reported that the rate of claims by coalminers for sickness benefit was two and a half times the national average. The serious implications of these rates made a careful assessment of their accuracy essential. This paper discusses cooperative studies carried out by the General Register Office, the London School of Hygiene and Tropical Medicine, the Ministry of Pensions and National Insurance, and the National Coal Board Medical Service to examine the accuracy of the reporting of occupation on the various records concerned. The numerators of occupational mortality and morbidity rates derive from job descriptions on death certificates and claims for sickness benefit respectively. The denominators of the rates come from entries of occupation on Census schedules. Errors may occur in both. There are many diverse occupations in the coalmining industry and each may have different names in the various coalfields. Many hundreds of names are listed in the instructions prepared by the General Register Office (1951) and are used for classifying occupations in all three sources of material for mortality and morbidity rates. The occupations are grouped into eight classes, given the codes 040 to 045, 047, and 049 as detailed below. In the studies reported here, descriptions of occupations on death certificates, on claims for sickness benefit, and on Census schedules have been checked against the best available evidence of actual occupation obtainable from sources within the industry or outside it. The coding actually made on official