This research project is structured around three objectives, targeting people aged 75 and over, to assess their need for help, the nature of the help they receive, and the extent to which their needs are met. Objective 1: to measure their need for help in carrying out daily life activities. Objective 2: to quantify and qualify the help received in carrying out daily life activities. Objective 3: to measure the degree to which the need for help is met: needs are either met, insufficiently met, or not met. Problem area 1: factors explaining the heterogeneity of cases of loss of autonomy and compensation for the loss of autonomy. Problem area 2: estimation bias and treatment effects identified in health surveys of the general population.