Case Studies

CalEnviroScreen

The CalEnviroScreen data set compiles various pollution, health, and demographic data for each census tract in California.

The data is available in the raw form in a spreadsheet and the CES website creates maps that color-code the data.

The CES maps are a version of a choropleth map. These choropleth maps use color to show the percentile of each area in the overall data set of California census tracts.

Note that there are at least two ways where these data are summarized and lose detail.

• The overall score is a composite of all of the pollution and health factors.
• The score for a geographic area is over the entire census tract.

CSU Data

There are 23 CSU campuses which is a manageable number for plotting data by hand.

• CSU enrollment data
• CSU cost comparison

State Data

There are 50 states in the US which is also a manageable number for making histograms by hand.

• US Data by State
• Wikipedia State Populations

County Level Health Data

• County Health Rankings and Roadmaps
  • Data Downloads page

Drawing a Histogram

• identify source of data
• identify what each data point will be
• find maximum and minimum of data
• decide on number of bins and bin ranges
• tally data points in each bin
• draw rectangles proportional to data points in each bin