One of the greatest advances in modern public health and medicine was the enumeration of mortality and disease rates and their longitudinal trends for the total population and for age, sex, locality, and other groups. This great innovation resulted from the discovery that statistics on births, deaths, and other social behaviors in geographic regions showed striking regularities from year to year. The enumerations were soon recognized as being of great practical value by governments. The United States government pioneered in developing the census while European governments assumed leadership in vital statistics.

Public health and medicine were held back for centuries by the inability to obtain the most basic quantitative information: the proportion of the population that died each year; death rates by age, sex, and other characteristics death rates by cause of death; and birth rates. The lack of interest was based on two beliefs: with rare exceptions, deaths and births were private affairs of interest only to the families involved; and the rates varied so much from year to year that enumerations would be of little value.

In the late eighteenth and early nineteenth centuries, some European governments began to publish occasional statistics on births, deaths, and marriages. Observers were amazed to discover that the statistics were remarkably consistent from year to year. As examples, the number of suicides in France varied between a low of 1,542 and a high of 2,048 annually between 1827 and 1831, and accidental deaths varied between 4,478 and 5,048 annually over the same period. Yet each suicide results from a highly idiosyncratic individual decision and each accidental death is unpredictable by definition.