A methodological approach based on indirect sampling to survey the homeless people

The Italian National Institute of Statistics carried out the first survey on homeless population. The survey aims at estimating the unknown size and some demographic and social characteristics of this population. The methodological strategy used to investigate homeless population could not follow the standard approaches of official statistics usually based on the use of population lists. The sample strategy for the homeless survey refers to the theory of indirect sampling, based on the use of a sampling frame indirectly related to the target population. Following the indirect sampling approach, the estimation is performed through the “weight sharing method”, based on links connecting the frame of services with homeless population.