Thousands of Hamiltonians are set to take part in a test census today.
It's being conducted to see how changes made to the data collection process would work in a real nationwide setting.
Stats NZ is keen to avoid a repeat of the 2018 Census, which had the lowest turn-out in half a century.
Census General Manager Kathy Connolly says the test will run in Hamilton East and Hamilton West, and involve more than 17,000 people.
"We hope to learn whether their changes are working and if further tweaks need to be made for the next nationwide setting in 2023."