Assignment #8: Data Classification and Choropleth mapping

Part 1: Select a data value and classify in four different ways. Create a legend for each and save in a single "legend.png" file. Include the number of data values in each category.

Part 2: EXTRA CREDIT - Create a choropleth map of the "best" classification. Save as a compressed png24 file using Save for Web and Devices. Insert into a web page as described below.


Part 1:

  1. Download this table of data on US by state. Choose one of the data columns and classify the data into 5 categories using the equal interval (equal steps), quantile, natural breaks, and standard deviation approaches.
  2. Determine the number of observations in each category using the Excel FREQUENCY function. This video explains how this works.
  3. Create a legend for each classification method, as depicted below, that includes the number of observations in each category. Use this Illustrator template file. Save as "legend.png"
  4. GRAD STUDENTS: Also Range-grade the data between 0-100 based on this article. Use a perceptual adjustment on the grey shades. Create the "legend.png" file with 10 sample values that are equally spaced between the minimum and maximum values.


Part 2 is extra credit

  1. To make the map, you need an outline map of the US in Illustrator or EPS format. Search for EPS clipart. EPS is a file format that is commonly used for vector graphics.
  2. Give-up? Use this map, originally from It has some problems that will need to be corrected. Or this map, originally from
  3. Shade the states. Add the source of the data at the bottom right (U.S. Census Bureau), your name at the bottom left. Neatline.
  4. Insert finished map into a simple web page titled proj6.htm, like this:

<head> <title> Map of Unemployment in the United States by State 2012 </title>
<meta name="description" content="Awesome Description Here">
<meta http-equiv="content-type" content="text/html;charset=UTF-8"></head>
<h1>Title of map here, year</h1>
<img src=proj6.png>

“description” content= tells the search engine what your page or site is about: For the search engine to understand what your page is about, you need to write a good description. When Google's algorithm decides a description is badly written or inaccurate, it will replace that description with its own version of what is on the page. Writing a good description not only helps keep Google from rewriting it, but also helps you get good more people clicking through to your site. A well-written description not only tells users what is on your page, but also entices them to visit your site. A description is what shows up here in the search engine results. It is like good window dressing. Sites with poor descriptions will get less click throughs and the search engines will demote your site in favor of other sites.