Published online by Cambridge University Press: 03 October 2014
In England and Wales prior to 1956 annual estimates for the infant mortality rate q0 were obtained as the quotient of an observed number of deaths and an exposure calculated by reference to the related births. Since 1956, however, infant mortality rates have been measured as the ratio of the numbers of deaths and births in a given calendar year (cf. reference 4, Part I, supplement to Table 24).