GIS 5935 - Data Quality Assessment

Like the second assignment, this module continues to focus on data quality. More specifically, this week focused on data quality of road networks. As such, we were tasked with performing a comparative assessment to determine the completeness of a street centerline shapefile and a Topologically Integrated Geographic Encoding and Referencing (TIGER) road shapefile for Jackson County, Oregon. 

To perform this assessment we utilized a non standard method, based on that used by M. Haklay in the "Comparative Study of OpenStreetMap and Ordinance Survey datasets" in 2010. This included using a grid, which encompasses the study area, to clip the road network into smaller sections. These smaller sections give more detailed insight into areas which may be considered complete or incomplete. Once the roads were clipped to each grid cell/section the lengths were calculated and then compared. 

My analysis determined that 134 of the grid cells/sections contained parts of the street centerline file that were more complete, while 163 of the grid cells/sections contained parts of the TIGER roads file that were more complete. 

The image below shows a map displaying the geographic pattern of the differences in completeness for both road networks. In this map the cells/sections displayed in orange show a negative percent difference, indicating that the TIGER road network is more complete. While the cells/sections displayed in green show a positive percent difference, indicating that the street centerline network is more complete. 





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