Module 3 GIS 5935

In this module we are carrying an assessment of completeness. Completeness is defined by Mordechai Haklay as "the measure of the lack of data" (Haklay, 2010). In our particular case we are comparing two road data sets to determine which one is more complete. We were provided two sets of road data and a grid to overlay over the given area. Our job was determine which road data set is more complete based on which data set has the greatest length in kilometers and which dataset has the greatest length within individual grids. 

To start our analysis I used the intersect tool to join each road data set with the grids layer. Carrying out the intersect joined the attributes tables of the both roads and grids layers and allowed me to split roads and road segments by grid. Once the roads were separated by girds the next step was to quantify all the roads data. I used the dissolve tool to dissolve individual road segments into a single feature within each of the 297 grids. The dissolve tool could be used because we did not need the other associated attribute data for any other analysis. If we needed to preserve other attribute data a different solution would have to be found. Once the total length of roads in each segment was calculated we used formulas to determine the percent difference in the data. A map with graduated colors shows the percent difference in the two data sets examined. Individual gird cells could be tabulated and a statement of completeness could be made. 

Below is my final map showing the percent difference between data sets. 

 

References:

Haklay, M. 2010. How good is volunteered geographical information? A comparative study of OpenStreetMap and Ordnance Survey datasets. Environment and planning B, Planning & Design, 37(4), 682. 

Survey datasets. Environment and planning. B, Planning & design, 37(4),

682.