2001 Post-enumeration Survey


The 2001 Post Enumeration survey was the second survey run by Statistics New Zealand. In principle, a post-enumeration survey is a special survey undertaken shortly after the census to evaluate the completeness of census coverage. It involves an independent re-enumeration of a statistically designed sample of all dwellings covered by the national census. Post-enumeration surveys are an essential feature of census-taking in many countries. Post-enumeration Survey (PES) was conducted shortly after the 2001 Census of Population and Dwellings. Like the first PES in 1996, its main aim was to provide information on the completeness of census coverage – to gauge how many New Zealand residents were missed or counted more than once in the census. Statistics New Zealand intends to draw upon the PES results to adjust the population base for deriving post-censal population estimates and demographic projections. Users of census and population data will find this report informative and useful.

It is important to note that a post-enumeration survey is one aspect of examining the quality of census output and processes. As such, the 2001 PES will assist Statistics New Zealand in developing an enumeration strategy for the 2006 Census of Population and Dwellings.


The 2001 PES was a sample survey of individuals in permanent private dwellings and was undertaken two weeks after the 2001 Census of Population and Dwellings (held on 6 March). The objective of the PES was to measure the level of coverage (undercount/overcount) in the 2001 Census. The survey did not aim to check the general accuracy or quality of the responses to specific questions in the census.

Citation Information


2001 Post-enumeration Survey

Alternate Title

2001 Post-Enumeration Survey; 2001 Census Post-enumeration survey; 2001 PES


Statistics New Zealand: Population Statistics


Statistics New Zealand


Statistics New Zealand

Coverage Information

Temporal Coverage

  • 2001-03 to 2002-07

Topical Coverage

  • Population and migration
  • Census of Population and Dwellings
  • Census
  • Undercount
  • Overcount

Significant events impacting this study series

The 2001 Post-enumeration Survey (PES) was the second undertaken by Statistics New Zealand, with the first undertaken five years previous to measure the coverage of the 1996 Census. The 2001 survey adopted a similar methodology to the 1996 survey.

While analysing the 2001 data, two methodological issues were uncovered in the 1996 survey which led to a revision of the 1996 PES results: - A small number of individuals were omitted from the 1996 PES calculations. This occurred where individuals matched to dwellings classed as unoccupied in the census were given a post-stratification factor of zero. - The 1996 eligibility criteria were overly restrictive, as they excluded all individuals in dwellings where there were some inadequate responses. The use of more conservative eligibility criteria used in deriving results from the 1996 PES partly reflected the fact that this was the first such survey conducted in New Zealand.

The revised 1996 net under coverage estimate was 60,000 people or 1.6 percent (+ 0.2 percent), whereas the original estimate had been 43,000 or 1.2 percent (+ 0.2 percent).


6 Five-yearly

Usage and limitations of the data

Because of the small sample size in the PES, the survey cannot provide reliable results below the published levels.

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