Admin data is the information you provide to government agencies.
It is your personal footprint every time you need help from the government or need to play your part as a citizen. It could include getting medical help, education, benefits, as well as things like births and deaths and tax information.
So admin data is real – not guesswork. It is becoming increasingly common, internationally, to use administrative data to estimate the population.
Some countries no longer take a traditional census. Instead, they use administrative data to keep a count of their people.
The use of administrative data in the Census is new in New Zealand. However, data from administrative sources has always been used to update the New Zealand population count every year between censuses.
It is also used to calculate the value of goods and number of people crossing our borders. And it is the basis for how we understand economic activity and aspects of environment. So administrative data is a cornerstone for quarterly economic growth.
We know that in the 2018 Census we missed more of the people who have historically been hard to collect a census form from.
However, many of these people do make use of government services. This means that although we don't have all the information we collect via a census form, we do have good data to count them in the place they live.
As a result, we have more detailed information about those who have been traditionally hard to count, including Māori.
We used ethnicity and Māori descent data from reliable government data sources such as birth records, and the 2013 Census, to reduce the level of missing data in the Census dataset.
As a result, both ethnicity and Māori descent data have a high-quality rating.
However, in April 2019 we announced we would not release official statistical counts of iwi, because of the level of missing iwi affiliation data, and the lack of alternative government data sources to fill the gaps.
We acknowledge this is a significant loss and are working in partnership with the Data Iwi Leaders Group, Māori interest organisations, iwi, and Māori to find real and relevant solutions.
The Māori electoral population is calculated using a statutory formula that includes the Māori descent data. Iwi affiliation data is not used for this calculation.
While Stats NZ did not expect to have to use admin data so much when we began the 2018 Census, we have been working on the idea of using admin data to deliver a population census for seven years.
We've taken a careful approach to this idea, to avoid errors.
We need to be certain someone exists and is still living in New Zealand before they get added to the combined Census.
But the use of administrative data doesn't fix everything – it is not a silver bullet.
It has very much been on our mind that new methods and new data sources bring new issues.
We have examined the 2018 dataset more extensively than in any previous census; we have undertaken quality assurance activity ourselves and independently to evaluate the dataset that has been produced; we have set up an external data quality panel and carefully considered their expert advice and opinions and we are seeking international peer review of methods, compiling thorough documentation, and providing detailed quality indicators so users can make well-informed decisions about how they use data from the census for a range of different questions.
While this is complex, we will describe everything we know when we release the data, and discuss any concerns.
Useful links:
https://www.stats.govt.nz/2018-census/
https://www.stats.govt.nz/news/customer-update-on-data-quality-of-2018-census
https://www.stats.govt.nz/news/2018-census-external-data-quality-panel-confirmed
Vince Galvin is chief methodologist, Stats NZ
