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Urban planning, estate management, architecture

Planning and the built environment

Location is a variable. ZStat treats it as one, rather than as a column of numbers that happen to be coordinates.

A regression on property prices with no spatial term treats two flats on the same street as independent observations. They are not, and every standard error it reports is too small as a result. These procedures are the ones planning, valuation and architectural research actually use.

What you can do

Moran's I gives one answer for the whole study area: clustered, dispersed, or indistinguishable from random. Tested by permutation rather than an approximation that assumes what is under test.

What it refuses

  • Treating latitude and longitude as plain x and y. A degree of longitude is 111km at the equator and 96km at Kano; distances are computed on the sphere.
  • Hiding that a hot-spot map runs one test per location, so on a hundred places about five look significant with no pattern at all. What matters is whether they are next to each other.
  • Pretending it can tell whether your coordinate columns were swapped. In Nigeria both fall in the same numeric range, so nothing detects it and the result says so.
Bring coordinates in decimal degrees. A study area taken from the bounding box of your own points is smaller than the real one, which makes any pattern look more regular than it is.

The other parts

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