How segregated is Auckland, and New Zealand?

A story published on the Newsroom site last month discussed diversity and segregation in Auckland:

How often do we hear that Auckland is this wonderfully diverse city where immigration has produced an exciting multicultural mix and made it a truly dynamic city to live in?

The portrayal of Auckland as a place where different ethnicities live side by side and share the fruits of its booming economy suits many narratives, but is it a myth?

Associate Professor of Pacific Studies at the University of Auckland Damon Salesa says the residential segregation in Auckland is remarkably high in Auckland, and not far behind what you would find in South Africa or parts of the American South.

“The most segregated population is actually European New Zealanders in Auckland. These people have no window or vision on the rest of Auckland…. the city many European New Zealanders live in is not diverse at all."

Now, I've been working for the last couple of years on developing new projections of future ethnic diversity as part of the MBIE-funded CADDANZ (Capturing the Diversity Dividend of Aotearoa New Zealand) project. Those projections make use of some fairly sophisticated population projections and microsimulation methods, but I won't be talking about those here just yet. And given continuing record rates of net migration, understanding these changes is pretty important.

Before thinking about future diversity, it pays to have a good understanding of current and past diversity. So, my very able research assistant Tobias has been working on estimating measures of segregation and isolation for New Zealand (and Auckland) recently. And it seems that Salesa has things quite wrong, based on the data (or he's reading the data quite differently to us).

There are several ways of measuring the extent of segregation of a population group (by which I mean how separated a given population group, such as Europeans, is from other population groups). Two widely used measures of residential segregation (for groups) are:

1. The Index of Segregation (IS), which measures the proportion of people in a population subgroup that would have to relocate in order to make their distribution identical to that of all other groups (on average); and
2. The Modified Isolation Index (MII), which measures the extent to which members of a population subgroup are disproportionately located in the same area as other members of their group. 

Both measures range from 0 (low segregation or isolation) to 1 (high segregation or isolation). I'll focus on the Index of Segregation in this post (but the MII results are similar [*]). To calculate the measures we use data from the New Zealand Census 2001-2013 based on the number of people belonging to each of five ethnic groups (European, Asian, Maori, Pacific, and Other). [**]

First, here's the picture for the country as a whole:

Clearly, the most segregated ethnic group is the Pacific group, and segregation of that group has been declining since 2001. The Asian group is the next most segregated, followed by European and Maori (which are about even). The "Other" ethnic group is the least segregated of all. So, that doesn't seem to support Salesa's assertion that Europeans are the most segregated ethnic group. Also, they haven't been becoming more segregated over time. But his statement was about Auckland, so here's the same picture for Auckland:

Again, the Pacific group is the most segregated. Asians are clearly less segregated in Auckland than in the rest of the country, and in Auckland there is little to choose between that group and Europeans. Maori are also less segregated in Auckland than in the country as a whole, but notice the trend towards less segregation for Maori is the same for both Auckland and the whole country. Again, there is little support for Salesa in these data.

Those first two charts are based on data at the area unit level (an area unit is a geographical unit that in urban areas equates roughly to the size of a suburb). You might worry that using these arbitrary boundaries matters, but it doesn't much. Here's the picture for the whole country based on 2014 electoral boundaries:

Notice that it doesn't look much different from the country as a whole using area unit boundaries (the first chart in this post), in terms of the ranking of the different ethnicities' levels of segregation (and if we look at electorates in Auckland only, it looks similar to the second chart in this post). Overall, we can probably conclude that the European ethnic group is not the most segregated (in Auckland, or in the country as a whole). If we are concerned about segregation, we should be looking at the Pacific and Asian groups (and particularly the Pacific group in Auckland).

As a bonus, it's interesting to note that New Zealand is much more segregated by ethnicity than by political affiliation. Here's segregation by vote share from the last five national elections (2002-2014) plotted on the same scale (and with five groups, to make it most comparable to the ethnic segregation data above):

New Zealand is much less segregated politically than ethnically, and none of the political parties' supporters seem vastly more segregated than any other (though I wonder if Labour and NZ First will continue their previous trajectories through this year's election)?

*****

[*] The MII results accentuate some of the differences, and some of the rankings are slightly different, but the overall picture is the same in that the Pacific group is the most isolated.

[**] These calculations are based on the 'total response' ethnicity for each area. In the Census, people can report that they belong to more than one ethnic group, and the 'total response' counts these people once for each group they belong to. So, the total number of reported people by ethnicity in an area will always be greater than the total number of people in an area. I can't see that this would bias the statistics in any serious way, however.