On Calculating Crude Death Rates in the Pacific Labour Trade

In the Pacific labour trade, data on the annual number of deaths of indentured workers and the population of indentured workers at January 1 each year are usually available, so that annual crude death rates can be expressed as the number of deaths in a year per 1,000 of the mid-year population. The mid-year population is used as an approximation to the average population exposed to risk of death during the year, and it can be estimated by taking the average of the population for two successive January 1 dates (Shryock, et al., 1973:2:394).