I placed some cones on a sports playing field and estimated their locations using latitude/longitude coordinates. An example pair of estimated latitude/longitude coordinates is 54.96975, -1.51407.

On average, my estimated latitude was 0.00009 away from the actual latitude. On average, my estimated longitude was 0.0001 from the actual longitude.

Am I able to say, on average, what distance my estimated coordinates were from the actual coordinates?

  • so you are trying to measure the bias from actual coordinates to the ones measured? – nickves Feb 13 '15 at 13:08
  • 1
    You may want to add what gis software you're using in your tags. You may also want to search threads and/or wikipedia about the accuracy of coordinates. When you get past a few decimal places in decimal degrees, you're talking about a very small difference, e.g. en.wikipedia.org/wiki/Decimal_degrees – recurvata Feb 13 '15 at 13:12
  • @nickves not exactly the bias, just the average distance in metres between actual and estimated coordinates. So on average, if the latitude was 54.96975, I would estimate the coordinate as something like 5.96980. What distance is this in metres? – luciano Feb 13 '15 at 13:30
  • So I reckon, on average, I was about 10m out. Sound about right? – luciano Feb 13 '15 at 13:32
  • How did you "estimate" and how did you "know" the lat-lon coordinates? Also, please edit all extra information into the question. – Martin F Feb 15 '15 at 1:22

The process should be:

  1. Project your data.
  2. Project the known points.
  3. Measure the distances.

Your comments indicate that you've decided you were "about 10m out," but why not just measure it properly and have the "right" answer (according to the projection you choose)?

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