Aaron Schiff’s blog

More dotmaps: young(ish) versus old(ish)

The NZ population dotmaps I posted the other day generated quite a bit of interest and I’m very grateful to everyone who emailed or tweeted with comments.

I received a few suggestions for other maps, one of which is a comparison of changes in population of young(ish) and old(ish) adults. The following maps show changes in the census usually resident population of people aged 20 – 34 and 50 – 64, ie the beginning and ending stages of most people’s working lives.

I decided to just look at cities, and lest I be accused of being a JAFA, I’ve made maps for Wellington and Christchurch too.

First, Auckland: The population of oldish adults has increased almost everywhere – can you spot the decreases? There’s a large population increase of both young and old in the central city, although more so for young. It’s around the city centre that the differences are most apparent.

Auckland young vs old

Next, Wellington. Again there are very few areas where the oldish population decreased, and the increases are relatively evenly distributed. For the youngish, a strong increase in the city centre is balanced by decreases in many surrounding areas.

Wellington young vs old

Christchurch is a bit special because of the effects of the earthquakes, but again different age groups appear to have responded in different ways.

Christchurch young vs old

A few notes for the sharp-eyed:

I’m making these maps by randomly scattering dots in census area units based on the change in the census usually resident population between 2001 and 2013. I haven’t used any information about where people actually live, which explains why there are dots on parks, airports, uninhabited islands, etc. This will distort the distribution of population in some area units where a lot of the area is actually uninhabited.

I wanted to do the analysis at the smaller meshblock level but a lot of the census population by age data is censored at that level, so I had to use the larger area units.

The source data from Stats NZ is here, and the 2013 census boundaries are here.

The colours reflect the overall net change in population between 2001 and 2013. In areas that experienced a net decrease in young population, for example, some young people may have moved in, but more moved out.