Housing Affordability Measure

Using household-level data from the Statistics New Zealand Integrated Data Infrastructure (IDI), The Housing Affordability Measure is a new approach to measuring housing affordability. First released on 10 May 2017 this measure provides a picture of shifts in affordability, broken down by region and territorial authority (and by ward in Auckland).

In August 2012, as part of a review of the Official Statistics System, Cabinet agreed that work should be undertaken towards the creation of a Tier 1 official statistic on housing affordability. The Housing Affordability Measure (HAM) is an experimental statistical series that measures household income after paying for housing costs for two subsets of the population: potential first home buyers population and renters.

Affordability is calculated by using data from Statistics New Zealand’s Integrated Data Infrastructure to measure income at the household level. Housing costs – the rent lodged on tenancy bond forms for renters and mortgage payments, rates and insurance for potential first home buyers – are then subtracted. The remaining household income is then adjusted to reflect the fact that larger households generally need larger incomes.

As the lead government agency on housing policy, the Ministry of Business, Innovation and Employment (MBIE) assumed the responsibility for developing these two indicators.

Latest release of HAM

Changes to HAM version 1.2

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. For example, the original HAM release was version 1.0, the HAM released in August 2017 was version 1.1 and the HAM released in June 2018 is version 1.2.

Changes from version 1.1

Data improvements

Two significant improvements to the HAM data are included in version 1.2:

  • Some households were being assigned to the wrong geographic areas, or were not being assigned to an area at all in version 1.1. This has been corrected in version 1.2.
  • MBIE has been able to improve the quality of address information being supplied to Statistics New Zealand. This means we can provide HAM data on a more comprehensive set of households than before.

These changes have had a significant effect on many Territorial Authorities, especially the smaller ones. Please replace your previous HAM data sets with the new data.

Method changes

Based on advice from the Reserve Bank, we have changed the interest rate used to calculate HAM Buy. The original interest rate used was the Effective Mortgage Rate which can be found on the Reserve Bank’s website. The new rate used is the 5-year fixed new mortgage interest rate. The new rates can be found on the Reserve Bank’s website as far back as December 2004, and we have used an unpublished back-series provided to us by the Reserve Bank to cover the period from January 2003 to November 2004. The main advantages of using the new interest rate are as follows:

  • It focuses on new mortgages specifically, making it more suited to estimating housing costs for first-home buyers.
  • Because it is a 5-year fixed rate, it accounts for banks’ perceptions of how interest rates are likely to change over the next five years. This makes it more useful to measure housing affordability in the medium-term.

Also, as the old interest rate was discontinued in December 2016, meaning that it could no longer be used for HAM Buy calculations.

This change has no effect on HAM Rent (as HAM Rent does not use an interest rate in its calculations), but does affect HAM Buy.

Difference between HAM Buy version 1.1 and version 1.2

[image] national change

While the two versions largely track each other over time, a significant difference between them emerged in 2009, and they started to converge again in 2010. This is the point at which the two interest rates were the most different; reflecting the uncertainty around the state of the economy during the early years following the 2008 recession.

Because the interest rate is applied to all regions of New Zealand in the same way, the effect of the new interest rate on HAM Buy is similar for every region.

First release of HAM

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

Read the first set of results.

We are interested in your feedback

Please email housinginfo@mbie.govt.nz if you have any questions or comments relating to HAM.