This is my second attempt to post this question since the answers to my first question were not as useful as I had hoped. The link to my first question is here: first question attempt

I am trying to solve a problem at a national level but am starting with Rhode Island to solidify my approach. Thus, everything in this question will be focused on the state of Rhode Island.

Here is the map I am starting out with: Starting Map The polygons are census tracts and the points are company office locations.

I’d like to figure out the following: For each census tract in Rhode Island, what percent of land area is covered by a certain company (total of 3 companies). Making sure that water area is not included in the calculations.

And just as an FYI, I am extremely new to GIS in general and have been going at this problem for a few days now. I am using QGIS 2.18.9.


I have 3 input files:

  1. The 2010 Census Tract shapefile (RI_Tracts) for Rhode Island with edited fields for simplicity:RI_Tracts
  2. A CSV file (RI_Tract_Tiers) that classifies each census tract into tiers 1-5:RI_Tract_Tiers
  3. A CSV file (RI_Offices) for office locations with the following fields:RI_Offices

Desired Output

A table that looks something like this:Desired_Output

What I've Tried

  1. Join the RI_Tracts table with the RI_Tract_Tiers table to classify the Tracts into tiers
  2. Color code the census tracts by Tract_Tier
  3. Import and buffer the company locations in the RI_Offices file
    • Buffer distance is 10,000ft (3048 meters), so I enter “0.030480” into the distance field of the Fixed Distance Buffer tool
  4. Dissolve the company locations by Office_Category to get rid of any overlaps b/w the same company
  5. Color code the company locations by Office_Category

Here is the map I end up with after performing the steps above:ending_map

This is where I get stuck. I have tried using the following tools to analyze the map and get the output I want (with no success):

  • Union
  • Intersect
  • Statistics by Categories
  • You can use the Clip Tool with [input layer: tracts] and [ clip layer: your dissolved buffer]. That will produce new tract_id based polygons. – NettaB Jun 3 '17 at 15:52

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