Sampling the Maori Population using Proxy Screening, the Electoral Roll and Disproportionate Sampling in the New Zealand Health Survey

This chapter describes an instructive example of a hard-­to-­reach subpopulation: the indigenous Māori population of New Zealand. This population shares some characteristics with others described in earlier chapters: it is relatively rare, over-­ surveyed, and geographically dispersed, and there is no adequate population frame. There are some unique features as well: Māori 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 Māori 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.