National migration series | Part 1: Trend or no trend?

National migration series | Part 1: Trend or no trend?

Planners know that migration is a powerful influence on future population – an influence much stronger than natural increase (births and deaths).

However, what planners struggle with is quantifying migration in the short and long-term future (and even in the short-term past!).

So if migration has such a significant influence on the makeup of our population, how do we account for the influence of migration when planning for the future?

Written by our New Zealand client manager, Penny Bloomberg, this blog is the first in a series that will explore national and regional migration trends in New Zealand, variables in migration, and the difficulties with current data sets.

Reading from Australia? Stick around.

While this piece uses data and examples of migration trends for New Zealand, it is a helpful guide for understanding the nuances of migration data, and the impact of migration on population change, for planners (and anyone interested in population forecasts) in Australia and beyond.

Annual migration figures can, and do, swing wildly

In our work with local government across Australia and New Zealand, we see councils under increasing pressure to made future planning decisions in response to short-term trends. Currently, the rise in net migration has gained a lot of attention, yet the data shows migration to be mercurial. The increase in net migration is not a trend – the trend is continuing volatility. Therefore any decisions made in response to the migration-driven portion of population change should be carefully considered.

So how accurate are migration figures and forecasts?

To find an answer it’s best to start with what we do know and work from there.

We do know that migration figures are up to record levels in 2017. We also know that migration figures can change significantly.

Immigration data collected by customs via arrival and departure cards provides an accurate picture of the overall migration flow (inwards and outwards) at a national level.

The following chart tracks net migration over the last 140 years (Bedford, 2017).

New Zealand Permanent and Long-term (PLT) net migration

PLT-Net-migration-640x359 Source: ( Bedford, 2017)

The last five decades are characterised by pendulum-like swings in the balance of migration.

For example, 1979 witnessed a 40,000-person net loss in population. Back then New Zealand’s 1979 population was just over 3 million, and the loss resulted in an overall population decrease, down 1,300 or 0.04% on 1978.

Conversely, in 1973 (just six years prior), the net migration of 33,809 contributed to a 2.2% population gain of 65,200.

Migration in context

Tracking almost a century-and-a-half of migration is pretty cool, yet these figures lack relevance until we give them some context.

Looking at net migration through a wider demographic lens gives a different perspective. When net migration is assessed against the total population count, you get a migration rate which shows relative change. The net migration rate for New Zealand shows a century of volatility ( Poot, 2014), with New Zealand fluctuating more than other Western countries ( Nolan, 2017).

But are we the only ones experiencing this trend? A view of more recent changes in the New Zealand migration rates, compared to other OECD countries, shows New Zealand’s current rate is similar to Australia’s 2009 net migration result and even less than Ireland, who recorded the highest rate of those countries selected in recent history.

A comparison of the change in the net migration rate of selected OECD countries


Source: Statistics New Zealand

So what does this all mean for forecasting migration’s influence on population?

The first conclusion in this series is a cautionary tale: while migration can have a significant effect on the population, it is difficult to accurately project because of its volatility.

However, a more in-depth understanding of the drivers and variables of net migration affords valuable insights for planners and forecasters. So far, we have only dabbled in the seesaw characteristics of net migration as a whole. Within that dataset are a number of contributing variables. One piece of the puzzle is inwards migration, which we’ll explore in more detail in the next blog in this series.

Read Part 2: Understanding incoming migrants

.id is a team of population experts, who use a unique combination of online tools and consulting to help organisations decide where and when to locate their facilities and services, to meet the needs of changing populations. We provide free resources to help you make the most of demographic data. Access .id’s demographic resources here.


Bedford, R. (2017). Publications. Retrieved from Knowledge Auckland:

Nolan, P. (2017, August). National population estimates: At 30 June 2017. Retrieved from Statistics New Zealand:

Poot, J. (2014, July). The migration roller coaster and house prices. Asia New Zealand Foundation Bulletin. Retrieved from

Statistics New Zealand. (2017, July). Trending topics – migration. Retrieved from Statistics New Zealand:

Penny - Population expert

Based in New Zealand, Penny primarily looks after our Kiwi clients but also lends her expertise to the Australian context. Penny has extensive experience as a Communication Manager in Local Government and has a degree in Business and Communications. She also brings a breadth of generalist management experience in fields as varied as research, civil defence, project and event management, marketing and training. Penny’s knowledge combined with the .id tools help clients work with their communities to empower grass roots decision-making, advocacy and grant applications, and focus on strengthening council-community relationships. Penny has a rural property and enjoys growing and eating food and wine, which she runs, walks, bikes or swims off, when she’s not in the art studio.

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