Housing Affordability Measure versions and disclaimers

This page explains the difference in the versions of the Housing Affordability Measure data series and the disclaimers for its use.

HAM is experimental and subject to change

As HAM is still an experimental series, MBIE will be making regular adjustments to the method used to create HAM, and how it is presented. Additionally, the data we use to produce HAM is constantly being refined and improved which could also result in changes to the series over time.

Because MBIE updates the full back series whenever a change is made, newly-released HAM results may differ slightly from previous releases.

Users should not combine data from different HAM releases. If you have any analysis that you want to update from a previous version, we recommend downloading the most recent tables.

Since HAM data from different releases are not necessarily compatible, MBIE has given a version number to each release:

  • The original HAM release was version 1.0
  • The HAM released in August 2017 was version 1.1
  • The HAM released in June 2018 was version 1.2
  • The HAM released in December 2018 is version 1.3

Changes from version 1.2 to version 1.3

Data improvements

Two improvements to the HAM data are included in version 1.3:

  • MBIE has further improved the allocation of households to the correct Territorial Authority. This has had a minimal effect on most areas, apart from Mackenzie District and Whanganui District (see below).
  • MBIE has completed testing on the data that allows us to provide more up-to-date HAM information. As such, we are now able to provide HAM up to March 2018, just under a 9 month delay. While MBIE will continue to investigate ways on making the data more current, it is unlikely that much more improvement will be possible as we are approaching the limits of the timeliness of the data contained in the Integrated Data Infrastructure.

Method changes

There have been no method changes to HAM in version 1.3.

Difference between HAM Buy version 1.2 and version 1.3

ham changes v2 v3

Note that the two Territorial Authorities have been presented here because they were affected unusually strongly by the data improvement – other geographical areas show negligible changes.

First release of HAM

The HAM’s first set of results, up to June 2015, presents the main findings about housing affordability trends at a national level and for the 3 most populous regions of New Zealand.

Files for download:

HAM v1.0 Results paper [PDF, 888 KB] - The key findings from the initial publication of the Housing Affordability Measure

HAM v1.0 Methodology [PDF, 1.4 MB] - The technical details behind how HAM was constructed.

Table 1 – HAM by Region [CSV, 33 KB] - Ham Buy and HAM Rent by Regional Authority

Table 2 – HAM by TA and selected Wards [CSV, 109 KB] - HAM Buy and HAM Rent by City and District Council. Also provides Ward-level information for Auckland.

Supplementary Table A – HAM by TA and Selected Wards (trended) [CSV, 163 KB] - HAM Buy and HAM Rent, but smoothed out so as to make it easier to see the trends over time.

Supplementary Table B – Alternate HAM thresholds [CSV, 445 KB] - Alternate versions of HAM that use the 30th or 10th percentile of affordability, instead of the median as a benchmark.

Disclaimers

The Housing Affordability Measure is an experimental series we produce.

It is not a Tier 1 Official Statistic, nor has it been endorsed by Statistics New Zealand. It has been created for research purposes from the Integrated Data Infrastructure (IDI), managed by Statistics New Zealand.

The opinions, findings, recommendations, and conclusions expressed in this paper are those of the author(s), not Statistics NZ.

Anonymised data

Access to the anonymised data used in this study was provided by Statistics NZ in accordance with security and confidentiality provisions of the Statistics Act 1975. Only people authorised by the Statistics Act 1975 are allowed to see data about a particular person, household, business, or organisation, and the results in this work have been confidentialised to protect these groups from identification.

Careful consideration has been given to the privacy, security, and confidentiality issues associated with using administrative and survey data in the IDI.

Further detail can be found in the Privacy impact assessment for the Integrated Data Infrastructure available from www.stats.govt.nz(external link).

Tax data

The results are based in part on tax data supplied by Inland Revenue to Statistics NZ under the Tax Administration Act 1994. This tax data must be used only for statistical purposes, and no individual information may be published or disclosed in any other form, or provided to Inland Revenue for administrative or regulatory purposes.

Any person who has had access to the unit record data has certified that they have been shown, have read, and have understood section 81 of the Tax Administration Act 1994, which relates to secrecy. Any discussion of data limitations or weaknesses is in the context of using the IDI for statistical purposes, and is not related to the data’s ability to support Inland Revenue’s core operational requirements.