% coverages (was RE: [postgis-users] Computing area in km^2 from 4326 geometries)

[Ethan Alpert]

Now that I've resolved my previous question I have a new one.

If my data is WGS84 lat/lons how accurate is computing %coverage? If I
do area2d(intersection(A,B))/area2d(B) will it give me a reasonable
value? I only need 2 significant digits for this one. If inaccurate how
can I determine a reasonable error range?

Thanks,

-e