Special Topics In GIS Lab 1

This week it was nice to get back to the grind by working with ArcMap and using the toolbox. We created buffer regions around an average location of fifty GPS points taken by the same device in the same location. The goal was to determine the precision and overall accuracy of the data or device itself. The results can be seen in the following map. I attempted to keep the layout simple and only show the needed data to understand the precision and accuracy aspects.

The point that was made this week in class is that accuracy and precision are two different things. Precision is measured as the distance a point sample is from the average of all of the point samples. The accuracy is measured as the distance the samples are from the reference point or the "True" location. The reference point measured 3.78 m from the average location of the way points taken by the GPS. This shows that the GPS location was fairly accurate. 3.78 meters is about the standard width or length of a bedroom in a normal house. For measurement tools from space that seems fair to call the average way point accurate. The horizontal precision of 4.85 meters seems in line with the accuracy of the average. I would question the results if the horizontal precision was much larger than the horizontal accuracy. Vertically the accuracy is 5.96 meters and the vertical precision is 5.8 meters. Again the numbers are fairly similar and small in scale. In my military experience these numbers would be fine for striking a large building, but if I was looking to strike a vehicle I would have a high probability of missing.