Etude exploratoire sur la connaissance de la mobilité à l'échelle régionale

Large surveys generally aim to provide reliable estimates at the national level and at levels sufficiently aggregated. Their sampling phase does not necessarily take into account certain subpopulations which we would subsequently be asked to provide estimates of level. The strong demand for results at a detailed geographic level, particularly from national surveys, has raised the problem of the fragility of estimates for small areas. This report addresses this issue with methods based on the sample design. These ones consist of building new weights for each statistical unit. The first method consists of optimizing the re-weighting of a sub-sample survey included in an area. The second one is based on the construction of weights that depend on the statistical units as well as the areas. Their precision, estimated by simulation with an application to real data, is quite close to that of the standard estimator. Then, the methods developed are applied to the estimation of local mobility indicators from the 2007-2008 French National Travel Survey. They provide sufficiently precise estimates. However, when the size of an area is small in the sample, the estimates obtained with the first method are not precise enough whereas the precision remains satisfactory for the second method.