In 2001 Statistics New Zealand improved the methodology used in the Household Economic Survey (HES) through the use of integrated weighting. This is a relatively recently developed method of adjusting the statistical output of a survey to match population benchmarks. In particular, it takes account of undercoverage in the survey of specified population groups.
Integrated weighting improves the robustness and accuracy of survey estimates. It also reduces the effect of bias in estimates resulting from undercoverage, as well as reducing the level of sampling error for benchmark variables.
This paper describes the method of integrated weighting that SNZ will apply to the 2000/2001 HES and outlines some of the expected impacts on statistical output. Given the wide range of uses of the HES it is not possible to outline all possible effects.
The paper examines the effect of benchmarks incorporating region, the number of people in the household, the number of households and on the age, sex and ethnic composition of the household members. As a result of feedback from users the age benchmark now includes the categories 0-4, 5-9 and 10-14 years. The general principles in the paper still hold however the changes in the benchmarks mean the detailed examples are indicative only.