Calculating Metrics for Spatial Data Quality

Horizontal Precision @68% 5.65meters

Vertical Precision @68% = 5.71meters

Horizontal Accuracy from the average point is 5.82 meters

Vertical Accuracy from the average point is 5.96 meters

Week one of Special Topics:  Learning Outcomes 1)understand the difference between precision and accuracy 2) calculate vertical and horizontal position accuracy and precision 3) calculate root-mean-square error (RMSE) and cumulative distribution function (CDF).

What is the difference between Accuracy and Precision?  Our text reports "Positional accuracy measures how close a representation of an object is to the true value." (Bolstad, 2017, p. 264).  And "Precision refers to the consistency of a measurement method." (Bostad, 2017, p. 264).  Another source describes it as "The accuracy of a measurement means getting a value that is close to the actual answer. Precision, on the other hand, refers to the reproducibility of this result that is you get the same result every time you try." (Nedha, 2015, para 1).  So precision is the repeatability of the results, and accuracy is how close to the referenced point (actual location).  

Precision for this lab was measured by calculating the % of precision desired (common is 68%) of the total sample points.  Sorting sample points from lowest to highest values and utilizing the measurements of the nth(68% of 50 sample is 34) sample.

Accuracy for this lab was measured by calculating the average of all sample points and comparing it to the referenced/actual point.

Reference:

Bolstad, P. (2017). Gis fundamentals: a first text on geographic information systems. Acton, MA: XanEdu.

Nedha. (2015, July 13). Difference Between Accuracy and Precision. Retrieved from https://www.differencebetween.com/difference-between-accuracy-and-vs-precision/