Visualizing Data in QGIS:

Basics of Styling & Symbolology

• Layer Properties
  1. Double-click the counties layers
  2. View layer information under different tabs at left
  3. On the Style tab, click Simple fill, then, under Symbol Lyer Type, choose a pretty Fill color
  4. Click “Apply”… You must click “Apply before clicking “OK” or changes won’t take

Explore the possiblities! QGIS has a very handy Color Picker tool, too.

Create a Table Join

1. Add the Boulder_Co_Tracts.shop layer from the workshop data folder
2. Next, add the Coulbder)Co)MHHI.csv file from the workshop data folder (this is US Census income data)
3. Now we must merge the attribute table of the Bopulder census tracts layer with the CSV table of median household income.
   • Double click the Boulder_Co_Tracts layer to open layer properties
   • On the Joins tab, click the green plus button to create a new join:
   • In the Add Vector Join dialog box, under Join layer, choose Boulder)Co)MHHI, then choose GEOID10 under both the Join and Target fields*
   • Click OK, then Apply, then OK. Open the Boulder_Co)Tracts attribute table to ensure the join occurred (right click the layer > Open Attribute Table)

*To join (aka merge) a data table to a vector layer’s attribute table, there must be corresponding identical fields in both tables—lucky for you, we prepared this data ahead of time!

Make a Choropleth map

Now that the income data has been added to the census tract layer, we can symbolize each tract based on median household income!

1. Open the Boulder_Co_Tracts layer properties
2. On the Style tab, choose Graduated

1. For Column, choose Boulder_Co_MHHI_MHHI2014
2. For Color Ramp choose a scheme that suits your fancy…
3. Click Classify
4. Click Apply!

You made a choropleth! Nice work!

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