+/- 4 meters = +/- 8 meters

Located in Assiniboine Forest, this geocache has been set up as a demonstration of the accuracy of handheld GPSrs. Everyone finding the cache is asked to log a waypoint of where you find the cache.

Sorry but I am no longer adding new points to the graphs.

The closest parking is at N49° 51'4.86 W97° 13'47.74 on West Taylor Blvd.

When using 2 GPSrs to mark a location (with good reception), tests have shown that sometimes the coordinates are remarkably close and sometimes they will vary more that double the "accuracy" shown by the perfectly functioning GPSrs. This is due to the random nature of which direction the GPSr is off the actual coordinates. If the 2 GPSrs happen to have an error in the same direction, then the coordinates are very close. If the 2 GPSrs happen to error in opposite directions, the coordinates then appear much further apart. Because of radial nature of the error (which requires a geometric and probability density explanation), most of the time the 2 GPSrs show a difference that is not perfect, but not the extreme. This unfortunately gives the user a false sense of consistancy, so when the accuracy differences are in different directions, they think something is wrong (bad coordinates) when actually nothing has changed.

For example if 2 GPSrs mark a waypoint with 4 meters accuracy, aprox 75% of the time the marks could be within 6 meters, often much better. But occasionally the marks will be 8 meters apart, with nothing changing exept the luck of the draw. In reality the effect is even worse as GPSrs can be optimistic about the "accuracy" they display, plus the averaging that some GPSrs use will penalize the impatient user! The punch line is that if a cache is logged with an accuracy of 4 meters, complaining about finding the cache less that 10-15 meters away only shows you don't understand the capabilities of a handheld GPSr.

If you go to find this cache, you are asked to:

find the cache
mark a waypoint at the cache location and record your accuracy
post your find on this page including your waypoint and the accuracy you had (To log a waypoint, just check the waypoint checkbox when you are typing your log and a set of boxes appear for you to enter your coordinates)
Sorry but I am no long adding new points to the graphs.

Please post the coordinates you actually marked. Being close to my coordinates does not make your waypoint more or less accurate. My GPSr is not necessarily better than yours and vice versa. I marked the location with an accuracy of 4m, using my GPSr's averaging function and approaching the cache from a few different directions.

Feel free to come back to this cache on as many different days as you like to see how a single GPSr can vary on different days!

Sorry but I am no long adding new points to the graphs.

Thanks for participating in this demonstration!

(Please be nice in the comments that you post. People hide caches for fun, so don't take away their fun, we need people to hide caches! Sorry, but to protect the delicate feelings of some of the people who helped set up this cache, complainy logs will be deleted without notice, thanks!)