Wednesday, June 4, 2008

Statistical Map


Statistical maps are used to display the distribution of a certain variable over a geographic area. In these maps each unit is represented by a shading technique or color that represents a value. The statistics shown on the map are expressed as rates, ratios, percentages, or other statistical measures.

2 comments:

j said...

Colorpleth maps can be misleading to compare areal data because the greater
the area you assign a value to the greater the impact of the color of the area on the person viewing it.
So you will see more important a great area with a small value mapped than an
extreme large data mapped onto a small area.
The other problem with the colorpleth maps, that visualiying pure counts can be
misleading. Compare the count of internet users in Israel and Egypt.
They fall into the same catgory with the shaded maps but the similar counts
occur on largely different areas.
This map suggests that position of Egypt is similar to Israel, because they
shade category is similar, and the impact of the greater patch of Egypt suggests that Egypt
is prior to Israel, but the fact is opposite: The absolute numbers are based
on a vastly different base counts (the whole inhabitants) and areas.
The right map would be here:
A cartogram, where areas would be the linear function of the
number of internet users in these countrise by 1000 people.

Elizabeth J. Neal said...

In these maps each unit is represented by a shading technique or color that represents a value. The statistics shown on the map are expressed as rates, ratios, percentages, or other statistical measures. fengshui