Module 3 - Data Quality - Assessment

 The goal of the accuracy assessment in this lab was to determine the completeness of road networks within Jackson County, Oregon. To conduct the analysis, the TIGER and Centerline roadways needed to be limited to the grids that were provided to us, which almost equally make up the entire extent of the county, with some outliers along the northern boundary. To do that, I utilized the modify features pane, specifically the clip tool and selecting the contain all lines option to clip out any part of the lines outside the grids. The next thing that needed to be done was to limit each roadway to a grid, even if it extends through multiple grids. This was done by utilizing the Split Features tool within the geoprocessing pane. This tool would split any lines into a new piece of data if the line transected across multiple grids. While these lines are limited to a grid, the appearance of the lines as one line is still present. Once the lines were isolated to their individual grids, it was now necessary to get the length sum for each roadway type in a grid. I utilized the summarize within tool in the geoprocessing pane to summarize the sum of each roadway in a grid. This allowed me to find the sum of both TIGER Roads and Centerline Roads to find the percent difference in each grid. To find the percent difference, I added the sums in Excel and utilized this formula: % 𝑑𝑖𝑓𝑓𝑒𝑟𝑒𝑛𝑐𝑒 = (𝑡𝑜𝑡𝑎𝑙 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑐𝑒𝑛𝑡𝑒𝑟𝑙𝑖𝑛𝑒𝑠 − 𝑡𝑜𝑡𝑎𝑙 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑇𝐼𝐺𝐸𝑅 𝑅𝑜𝑎𝑑𝑠) / (𝑡𝑜𝑡𝑎𝑙 𝑙𝑒𝑛𝑔𝑡ℎ 𝑜𝑓 𝑐𝑒𝑛𝑡𝑒𝑟𝑙𝑖𝑛𝑒𝑠) × 100%

Once I found the percent difference in each grid, I mapped out the differences in this choropleth map below: