Sampling the māori population using proxy screening, the electoral roll, and disproportionate sampling in the New Zealand health survey

Introduction This chapter describes an instructive example of a hard-to-reach subpopulation: the indigenous Maori population of New Zealand (NZ). This population shares some characteristics with others described in earlier chapters: it is relatively rare, oversurveyed, and geographically dispersed, and there is no adequate population frame. There are some unique features as well: Maori are less rare than many indigenous populations and have a special status in the NZ electoral system, so that the Electoral Roll provides a useful partial frame. A combination of strategies to oversample Maori in the NZ Health Survey is found to work well. A novel approach to setting the large number of design parameters required by this design is described, based on numerical optimization using a training and validation dataset. The Maori peoples are the indigenous population of New Zealand and as such are important for social, political, and historical reasons. They have higher rates of poverty and illness than the general population and so are a particular priority in public health planning. For all these reasons, many surveys in NZ aim to oversample Maori, to give more precise statistics than would be produced by an untargeted survey of the population.