# Is there a well-known way to compare the relative accuracy of 2 latitude/longitude results?

I have 2 geocoding results (in latitue and longitude) for a given address from different services. I'm interested in describing the results in relation to one another in terms of relative accuracy and am wondering whether there's a well-known algorithm for that comparison in the GIS world.

Let's say we have Result A, which we assume for the sake of this effort is 100% accurate. Then we have Result B and want to know inaccurate it is in comparison to Result A. Result A has 15 digits of precision while Result B has only 6, but even at the 6-digit precision the results are different.

Does taking the difference between the two results and dividing it by the "100% accurate" result and regarding that figure as the relative accuracy in percent even make any sense in GIS data? If not is there something else that does?

For whatever it's worth, this is at least partially an exercise in curiosity, since I'm fairly sure that at the resolution we need both results will be close enough.

• Hey Cori - Just a side note, before any comparison I would want to be sure both Lat/Lon coordinate pairs subscribe to the same Geographic Coordinate System (datum). For example, I'm unsure the comparison would be fair if your 100% accurate (control) point came from an NAD83 source, and the test point was pulled from a WGS84 dataset. Otherwise I'm not familiar with any routine accuracy comparison method, and am interested to see answers for your question. – Jim Apr 15 '16 at 18:32
• Thanks @Jim. I'll see if I can find out what datasets our respective points come from. – cori Apr 15 '16 at 19:15