The improving accuracy of the basic data and the exposed-to-risk of the English life tables.

1. THE English Life Tables Nos. 8 to 13 are based on the population figures by age obtained at the successive censuses of England and Wales from 1911 to 1971 and the deaths recorded in the three calendar years centred on the census year. Over this 60-year period there have been changes in the information sought regarding age at census and death registration and improvements in the exposed-to-risk formula; these are summarized in Table 1. 2. The crude rates of a mortality experience always show irregularities. If the data and methods of calculating these rates are accurate then the irregularities would be expected to be distributed in accordance with the binomial distribution