Sunday, September 10, 2023

Module 2: Data Quality Standards


For Module 2, we learned about data quality standards for spatial data accuracy.  The Positional Accuracy Handbook (1999) helped me learn about national standards of spatial data   accuracy and how to report a formal accuracy statement as required by the National Standard for Spatial Data Accuracy (NSSDA). Furthermore, we learned about the seven steps to apply these standards to our work.  I applied those steps to this assignment as follows:

1)      determined that we would be testing horizontal accuracy of the data sets.

2)     I created 22 test points within the study area  (various intersections in Albuquerque, NM)

3)     I created a point feature class for StreetMapUSA_Sample and created a point for the intersection closest to the test point data.  I also created a point feature class for ABQ_Streets_Sample and created points for intersections closest to the test points.  

4)     I populated all XY values for all points I created for ABQ_Streets_Sample and StreepMapUSA_Sample.

5)     I then calculated positional accuracy using the horizonal accuracy statistic worksheet.

6)     After calculating statistics, the GIS analyst would then prepare a formal accuracy statement. My statistics were off by a large margin, so I am in the process of getting assistance to ensure they are correct before I published them here.  With that said, once I figure out what I did wrong, I will add the correct accuracy statement.  The statement would be written as follows:

**Tested at XXXXX feet horizontal accuracy at 95% confidence level

**Compiled to meet XXXXX feet horizontal accuracy at 95% confidence level

It should be noted that 95% percent confidence level for horizontal accuracy is calculated by taking the RMSE and multiplying it by 1.7308.

Source: Positional Accuracy Handbook. 1999. Minnesota Planning, Land Management Information Center, St. Paul, MN



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