The organisation's staff includes statisticians, mathematicians, computer science specialists, accountants, economists, demographers, sociologists, geographers, social psychologists, and marketers.

The agency is a state sector organisation of New Zealand operating under the authority of the Statistics Act 1975.

For example, the census asks about the main means of travel to work, but by combining this with data from transport surveys, the department can issue detailed reports such as "Commuting Patterns in New Zealand: 1996–2006", with specific inferences such as "Over half of people who walked or jogged to work lived within 2km of their workplace.

It reports on labour costs, incomes, civil unions and marriages, employment, electronic card transactions, food prices, retail trade, births and deaths, prices of capital goods, overseas trade, screen industry, international visitor arrivals, overseas merchandise, agriculture and fish stocks, water resources, building consents, electronic card transactions, English language providers, wholesale trade, local authority information, balance of payments data, manufacturing surveys, commuting patterns, mapping trends, culture and identity statistics, housing trends, work stoppages, gross domestic product, industrial energy use, and the list goes on and on.

"[17] Their report was picked up by journalists at the Sunday Star-Times to form the basis of an article with the headline "New Zealand women stop having babies".

For example, in "Connecting the Clouds – the Internet in New Zealand", author Keith Newman cites agency statistics regarding telecommunications cost decreases (the Stats NZ report said "New Zealand average residential phone call pricing plummeted 50% between 1987 and 1993") and national finances (the Stats NZ report said "The current account deficit for the year ended March 2007 was $13.9 billion (8.5 percent of GDP)").

One gay activist felt Stats NZ was "breaking the law" by omitting a question on the 2006 census regarding sexual orientation; the article in the New Zealand Herald elaborated "Mr. van Wetering and the Office of Human Rights Proceedings, the independent legal branch of the commission, expect to discuss the inclusion of the (sexual orientation) question in the 2011 Census with lawyers for Statistics New Zealand later this year.

One blogger, claiming to be a former Wellingtonian journalist who identifies himself or herself as "Poneke", accused the Sunday Star-Times of publishing misleading data about crime statistics.

Poneke noted that “Statistics New Zealand now provide(s) the ability to query the New Zealand Police Statistics – allowing you to gather detailed crime information about your local area since 1994.” The blogger felt the agency was "impeccably impartial", but distrusted various media sources.

It lets users access specific information from past surveys, and collect it into a customised set of data.

[30] By using standardised codes, high speed computers can sift and sort through large databases to produce summary reports.

[33] The organisation's stated values are statistical excellence, integrity, confidentiality and data security, leading, connecting, and communicating.

For example, it published a biotechnology survey, based on a 10-page questionnaire developed by the agency, using scientific samples to choose respondents; the 2007 results can be downloaded to computers via the Internet.

[40] Statistical techniques such as sampling and weighting can reduce data gathering expenses while surveying, although it requires careful attention by statisticians.

If conditions do not permit representative sampling but known benchmark statistics are known (possibly from earlier census data), it is still possible to generate accurate information by weighting the data to distort it back, so to speak, to compensate for the distortion caused by the unrepresentative sample.

It is possible statistically to give men slightly greater weight to account for the discrepancy, and the result is more accurate data.

This is a relatively recently developed method of adjusting the statistical output of a survey to match population benchmarks.

A statement reads: "An important aim of our ongoing work is to understand, manage, control and report on all known sources of error... which simply reflect the inherent variability that exists among the units we are seeking to measure...

"[42] What greatly facilitates statistical accuracy by reducing non-response bias is that answering questions is sometimes required by law.

This requirement lessens agency expense, practically eliminates non-response bias (a perennial headache for most private market researchers) and improves accuracy.

For example, for the General Social Survey, people are selected randomly for 10-minute phone interviews which sometimes ask personal questions such as wage and salary information.

This policy is substantially different from countries such as the United States, where answering official surveys is rarely compulsory, including responding to its census which is done every ten years.

A user can learn that "89% of businesses use broadband to connect to the Internet" or that "145 babies were born on Mother's Day in 2008".

In the nation's early days, with a small population and before the advent of powered transportation and modern telecommunications, there was little need for statistics nor ability to create them.

One source writes: "As both New Zealand's population and the complexity of the information sought grew, so did the size of the army of temporary clerks that was employed every five years by the Census and Statistics Office to process it.

The drudgery of statistical work was gradually eased as adding and calculating machines and typewriters came into use, operated mostly by women.

Tabulating machines were imported from the United States in the 1920s to process punched cards; this too was women's work," according to a book written by David Green in 2002.

The well-regarded economist J.B. Condliffe worked at the agency after First World War, but no fully qualified mathematicians until after the Second, when in-house training in statistical methods also began.

The 2011 national census was cancelled due to the disruption and displacement of people caused by the February 2011 Christchurch earthquake.

On 13 August 2019, the Chief Statistician Liz MacPherson resigned following the release of a report criticising the department's handling of the 2018 New Zealand census.