How is location accuracy measured in Android?

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+1 Q:

How is location accuracy measured in Android?

Does anyone know the proper interpretation of the accuracy measurements returned by getAccuracy()? For instance, are they calculated as:

Circular Error Probability (meaning, if i understand correctly, radius of a 50% confidence circle)?
Radius of 95% confidence circle?
something else?

In addition, what are the actual calculations that are used and how much can we rely on them? Does it depend on the source of the location estimate (GPS vs. network)?

Many thanks for any advice you can give me.

+1 A:

The documentation on getAccuracy says that it returns the accuracy in meters. I would guess that this means if you get a return value of 60 you are somewhere in a circle with a 60 meter radius around the supplied position.

Janusz 2010-06-16 12:33:12

if i watch to my google maps and my current position you're right... in most cases. It also happened, that my phone showed my position about 2 or 3 kilometers away from my real position...I'm also interested in this issue

poeschlorn 2010-06-16 12:43:17

Thanks. I agree that the value returned by getAccuracy is in meters and that it must be the radius of a circle (or perhaps a sphere when altitude is also given in the location estimate). But there should also be a probability associated with it, and it's odd that the documentation does not say what that probability is or how it is arrived at. I've seen one posting online where someone suggested that it might be CEP, but that seemed to be just a guess so I would really like to find a way to confirm if it's that or a 95% confidence circle or something else.

John Palmer 2010-06-16 16:10:11

Here are a few links that are useful in understanding the question (but that don't resolve it):http://users.erols.com/dlwilson/gpsacc.htmhttp://groups.google.com/group/android-developers/browse_thread/thread/ce82882f81c1d65b?pli=1

John Palmer 2010-06-16 16:14:31

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How is location accuracy measured in Android?

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