Sampling and Weighting a Survey of Homeless Persons: A French Example

In 2001, the INSEE conducted a survey to better understand the homeless population. Since there was no survey frame to allow direct access to homeless persons, the survey principle involved sampling the services they received and questioning the individuals who used those services. Weighting the individual input to the survey proved difficult because a single individual could receive several services within the designated reference period. This article shows how it is possible to apply the weight sharing method to resolve this problem. In this type of survey, a single variable can produce several parameters of interest corresponding to populations varying with time. A set of weights corresponds to each definition of parameters. The article focuses, in particular, on “an average day” and “an average week” weight calculation. Information is also provided on the use data to be collected and the nonresponse adjustment.