Introduction

This chapter describes an instructive example of a hard-to-reach subpopulation: the indigenous Māori 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: 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.

The Māori 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 Māori, to give more precise statistics than would be produced by an untargeted survey of the population.