New Zealand in UN's top 20

New Zealand has the world's 20th-best record in human development, according to a major international survey.

The United Nations study ranks 182 countries by social as well as economic wealth and puts us ahead of economic powerhouses such as the UK, Germany and China.

Norway topped the list, with Australia second and Iceland third. Lowest ranked was African nation Niger.

The index is part of the annual Human Development Report released by the UN Development Programme, the part of the organisation headed by Helen Clark.

It measures countries' development by combining indicators of life expectancy, educational achievement and income.

New Zealand ranked high in life expectancy (11th), literacy (more than 99 per cent) and had the second-highest number of residents who had completed primary, secondary and tertiary education.

But we slipped down the list of GDP per capita, with the US$27,336 ($37,000) figure the lowest of the top 20.

Lead author Jeni Klugman said the report was first published in the early 1990s to show development wasn't restricted to financial factors.

It's compiled using international comparative data - the World Bank provides income details and the World Health Organisation provides life expectancy data, for example.

New Zealand has filled 18th, 19th or 20th spot on the index for each of the past 11 years.

But Klugman warned the data for this year's report was from 2007, before the global financial crisis hit.

She said "a bunch of countries would have gone down on the list" since then - including New Zealand which had suffered negative growth.

Klugman said some countries would have suffered in other areas, such as school enrolment rates, where families could no longer afford to send their children to school.

Other factors, such as crime rates and inequality, were not included in the index, because not all countries collect such data.

"Once you start picking and selecting data, you start cutting out countries. For example inequality - to add this in the study would cut out half the countries.

"We're not purporting that this is comprehensive. It's fuller than using GDP alone."

BNZ chief economist Tony Alexander said there was a "whole list" of reasons why New Zealand has a lower GDP per capita than other countries. They included a failure to grow the export economy over the past 30 years, geographical isolation and a small domestic market and there was "no easy answer".

New Zealand often fares better in other surveys. A survey by human resource company Mercer released this year ranked Auckland fourth-equal best city for quality of life.

Senior demographer at Statistics New Zealand Kim Dunstan said the UN's index was more thorough than some others.

"You can expect far more impartial information from agencies like the UN."

And while New Zealand was ranked 20th, there was little difference between us and higher-placed countries.

"It could be a trap to be caught up in rankings - there looks like there is no difference in some of the rankings," he said.

The report has a different theme each year. This year's is titled Overcoming Barriers: Human Mobility and Development. It focuses on migration and discusses "who migrants are, where they come from and why they move".

Klugman said the ranking could make New Zealand an attractive destination, but most people who moved, did so within their own country.