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We are calculating Population and geocoverage in mapinfo. We have calculated population coverage as an area overlap. How do we calculate population coverage if we have population defined for each polygon?

coverage

1. Are there any particular method to calculate population coverage for each boundary?

2. Any documentation and detail for analysis (not only steps but reason) would be helpful.

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1 Answer

Kitex

You could do a SQL Select that would calculate the areas. MapInfo Professional also has a built-in ProportionOverlap() function that could be used to calculate the proportion/percentage.

Select BORDER.ID, CartesianArea(Overlap(BORDER.OBJ, COVERAGE.OBJ), "sq m") "Overlap"
   , ProportionOverlap(BORDER.OBJ, COVERAGE.OBJ) "PropOverlap" 
   From BORDER, COVERAGE
   Where BORDER.OBJ Intersects COVERAGE.OBJ

The above select statement should work, but if your coverage table contains more than one object, you might want to group the result by the ID of the BORDER objects and Sum() the area calculation. Also the proportionaOverlap might not work correctly in this case.

Finally I can recommend that you take a look at the tool "ProportionalOverlap" that you can find the Tool Manager in the later versions of MapInfo Professional.

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Is there any advantage or disadvantage converting it into grid and doing calculation? –  kinkajou May 29 '13 at 7:46
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