[GRASSLIST:1580] Re: interpolate nominal values

[Lyle E. Browning]

Rich Shepard wrote:

>   While this might be computationally feasible, I suggest that it is
> meaningless in the real world.
>

Archaeologists use this sort of info all the time, although it could be argued
that we don't live in the real world either ;>)

>
>
> Suppose you had point (sites) data of fast-food restaurants (i.e., junk food
> vendors) from a typical American medium size city. The nominal data
> categories include "McDonalds", "Burger King", "Taco John", etc. Now,
> regardless of whether you use IDW, Veronoi diagrams/Thiessen polygons, or
> Krieging, you interpolate a 3D surface of these points. How do you interpret
> the results? What will it tell you (or me, for that matter)?
>

Isn't that exactly the kind of info that those fast-food mega-corps used in the
first place to locate their gut grenade establishments? Population dynamics,
transportation nodes, economic bases, etc. I've been waiting for an opportunity
to use point data of that sort to relate population to water powered mills from
maps. Taking a county in the 19th century from a typical map which shows mill
symbols, one assumes (I know the acronym) all the mills are shown. Raw material
has to get to market by either water or road, so one is dealing with either a
custom or merchant mill. Using densities of mills, one can theoretically work
out population densities and correlate them with standing historic structures.
Leads to holes in the data with very much too large service areas, hence we go
look for more mills.

17th century potteries are a similar situation. One finds pottery, but no kiln.
Using the finds locations, one should be able to discern movement and the
central point of highest density which should be the kiln.

Lyle