April 4, 2017

How big is that (2)

In yesterday’s Official StatsChat Bogus Poll, about two-thirds of the respondents got one of the reasonable answers.

Here’s how we could work out most of the answer without looking it up.

First, a hectare is 10,000 square meters, or 2.5 acres (you might need to look that up).

Now, a ‘full section’ for a house is typically less than 1000 square meters (a quarter acre), so you get 10-20 of them per hectare, and maybe 100,000 of them in 7000 ha.  That’s definitely bigger than Eden Park, and it’s pretty clearly bigger than One Tree Hill Domain + Cornwall Park.  In the other direction, 100,000 full sections must be smaller than the Auckland isthmus, and so (look at a map) smaller than Manukau Harbour.

The comparison to Epsom electorate is a little harder, and you might need actual data to decide.

Now, actual data:

The areas are

Eden Park:  originally `about 15 acres’, or 6 ha

One Tree Hill Domain + Cornwall Park: 270 ha

Epsom: 20 sq km, so 2,000 ha

Manukau Harbour: 394 sq km, or 39,400 ha.

Waikato Region: 2.5 million ha.

If you look up the area of  the Auckland isthmus for comparison with Manukau Harbour, you’ll probably get a figure of 638 sq km. That’s the area of the old Auckland City: it includes the Gulf Islands that were part of the city (in particular, Great Barrier and Waiheke make up more than half of it). It’s surprisingly hard to find the area of the isthmus itself on the internet.

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Thomas Lumley (@tslumley) is Professor of Biostatistics at the University of Auckland. His research interests include semiparametric models, survey sampling, statistical computing, foundations of statistics, and whatever methodological problems his medical collaborators come up with. He also blogs at Biased and Inefficient See all posts by Thomas Lumley »

Comments

  • avatar
    Nick Iversen

    A hectare is 100m x 100m
    The square root of 7000 is a bit more than 80
    So 7000ha is 8km x 8km

    Easy but then I got lost. What in Auckland is 8km? Think, think.

    Rounds the Bays is 8km. Ta da.

    7 years ago