The discovery of regularities in social statistics led to efforts to use them to better understand the health and social conditions of the population. Physicians analyzed hospital and patient records and other investigators carried out social surveys of communities. Two investigators were especially effective in using statistics to understand health and disease. A physician, John Snow, used statistics to demonstrate the relationship between polluted water and the spread of cholera, and a statistician, Adolphe Quetelet, developed important new methods of categorizing and analyzing social and health data.

Hospital and Asylum Statistics

The discovery of regularities in social statistics and the researches of Pierre Louis soon led to statistical studies in many of the hospitals, dispensaries, and insane asylums established during the nineteenth century. These institutions brought together in one location large numbers of patients who were seriously ill and reasonably homogeneous because most were poor and urban. Hospitals were especially useful because the patterns of diseases among the poor in their communities could be measured by examining admissions and mortality rates and their trends for particular diseases and personal characteristics of the patients. Treatments could be evaluated because the patients could be retained in the hospital until the outcomes were certain and, if necessary, autopsied to determine the cause of death.

Many American physicians compiled hospital statistics and published them in medical journals and hospital annual reports. Although they believed they were providing quantitative descriptions of the health of the population, their methods were unsystematic and the samples inappropriate. The data were usually presented without explanations of their significance or comparisons with other hospitals or types of patients. Furthermore, hospital patients were atypical in that they were the urban poor in an era when most of the population was rural. They were in poor health because they were malnourished and lived in unhygienic conditions. They were very sick because most sought hospital care only when they could no longer be cared for at home.