Lab 1: Calculating Metrics for Spatial Data Quality

This week was the first lab in Special Topics in GIS.  The focus was on accuracy and precision of data.  Accuracy and Precision are important aspects of all data, including spatial data, and it is important to communicate the accuracy and precision of original data to the receiving audience.

As part of the lab, we were provided an array of waypoints that were collected from a single geographic point using a Garmin GPS device.  We then had to calculate estimates of precision and accuracy after we were then given the "true" reference location.  Below are two outputs of these calculations:

Horizontal Precision (68%): 4.45 meters
Horizontal Accuracy = 3.23 meters

Horizontal precision, which is a metric of the clustering of repeated measurements of a data point, was calculated by determining the average distance of all the repeated measurements to the average of these measurements.  The accuracy was calculated as the difference between the average point from the repeated measurements and a given "true" reference point.