Data for most dimensions of the What's My Gender Pay Gap? tool is taken from the Household Labour Force Survey, a sample survey of approximately 30,000 respondents which collects income information annually.

All statistical breakdowns are subject to sample error, including the national gender pay gap as reported by Stats NZ. Sample errors increase as further breakdowns are made, for example the gender pay gap between workers aged 15 to 19 is calculated using a very small source group.

In selecting data for What's My Gender Pay Gap?, the Ministry for Women has considered long-term trends to ensure any pay gaps reported are real and have continued to manifest over time.

The gender pay gap for most dimensions is calculated between groups as the difference between median hourly earnings. There is no standard measure of pay differences, and users may encounter other comparisons, such as those using averages (means) rather than medians. No matter how data is analysed, pay gaps between men and women exist and persist. 

Stats NZ calculates New Zealand’s official gender pay gap as the difference between the median hourly earnings of women and men in full- and part-time work. We use this same data and methodology.

Manatū Wāhine considers that by examining pay gaps by different populations, New Zealanders can best consider different solutions to reducing pay gaps for everyone.

As noted, pay gaps for fields of study have been calculated using the difference in median annual income, and are therefore not directly comparable to pay gaps reported for other dimensions.

Source data for the field of study report was derived from the Integrated Data Infrastructure (IDI), and provided to the Ministry for Women by the Tertiary Education Commission in 2019. IDI data is not subject to sample error in the same way as survey data, however it does suffer from some attrition where admin data sources cannot be matched. ‘False positives’ may appear when probabilistic matching incorrectly combines some records.

For more information on pay differences by qualification and detailed commentary, refer to earlier reports published by the Ministry of Education.