Household Economic Survey (Income) 2017/18

Information on New Zealand households’ income, housing costs, and material well-being is based on data collected as part of the Household Economic Survey 2017/18.

Period-specific information

This section contains data information that has changed since the last release.

Recall period

Recall period in the survey varies from latest payment made/income received, to payments made/income received in the last 12 months. As the survey was carried out continuously from 1 July 2017 to 30 June 2018, different households would therefore have different recall periods. Thus, households interviewed on 1 July 2017 would have recall periods earlier than the date interviewed, so from 1 July 2016 to 30 June 2017 while households interviewed on 30 June 2018 would have recall period from 01 July 2017 to 30 June 2018.

External influences

Changes in income and housing costs may be influenced by one-off real-world events. Events that could have influenced the HES 2017/18 data are:

• increase in the adult minimum wage from $15.25 to $15.75 effective 1 April 2017 and further to $16.50 effective 1 April 2018.

• increase in the starting out and training wage from $12.20 to $12.60 effective 1 April 2017 and to $13.20 effective 1 April 2018.

• New Zealand Superannuation rate (gross) increasing for single living-alone from $450.10 to $463.04 on 01 April 2018; single sharing from $413.60 to $425.55 on 01 April 2018; and ‘both partners qualifying’ from $340.80 each to $350.76 on 01 April 2018.

• low OCR kept short-term mortgage rates down.

Response rate for HES 2017/18

The sample size for HES 2017/18 was approximately 8,000 households. The achieved sample rate was 68.6 percent and our response rate was 76.3 percent.

Achieved sample rate compared with the response rate

The achieved sample rate is calculated as the number of eligible households that responded divided by the total number of dwellings sampled. Essentially, it tells you what percentage of the sample responded to the survey. Expressing the achieved sample as a rate controls for population growth.

The response rate is calculated as the number of eligible households that responded to the survey as a proportion of the estimated number of total eligible households in the sample.

The achieved sample rate differs from the response rate because it includes the ineligible dwellings in the denominator. This difference means that the response rate is particularly sensitive to the classification of household eligibility. As a result, the achieved sample rate is more stable over time than the response rate. We reached a response rate of 76.3 percent (post-imputation). While response rates have been declining over time, the impact of any bias arising from this is minimised by non-response adjustment and the calibration to population benchmarks.

Imputation for HES 2017/18

Imputation in HES replaces missing values with actual values from similar respondents. The table below shows the effect of imputation for the 2017/18 survey.

As a result of recovering and imputing records, the response rate for the year ended 30 June 2018 improved from 73.4 percent to 76.3 percent.

Sampling errors

We calculate sampling errors using the jackknife method. It is based on the variation between estimates of different subsamples taken from the whole sample. The tables below summarise the sampling errors between 2012/13 and 2017/18, by income source and housing-cost type. The tables also indicate the variability of the estimates between the six surveys. Customers should take care when interpreting income or housing-costs estimates with sampling errors greater than 20 percent – they are statistically less reliable than estimates with sampling errors less than or equal to 20 percent.