Many GIS organizations define precision and accuracy limits for their geospatial data and perform reviews of this data to ensure that standards are upheld. Accuracy is defined as "the closeness of agreement between a test result and the accepted reference value". Precision is defined as "the closeness of agreement between independent test results obtained under stipulated conditions". For this module, we determined precision and accuracy metrics based off provided data. The data provided was GPS waypoints mapped using a hand-held GPS device, a Garmn GPSMAP 76 unit.
The horizontal accuracy of 3.24 meters was determined by measuring the distance between the reference point and the average waypoint location. The horizontal precision is 4.5 meters. There is a significant difference of 1.26 meters. The vertical accuracy (average location elevation-reference location elevation) is 5.92 meters. The vertical precision is 5.9 meters. The difference between the vertical accuracy and vertical precision is 0.02 meters. There is not a significant difference between vertical accuracy and vertical precision.
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