The ‘tier’ chart is a simple alternative to looking at data in a table. Similar to a bar chart, a tier chart compares values among different categories. Its value lies in quickly communicating the differences in values among categories.
For example, consider the following table that shows the wins for every team in the National League Central for 2012:
Of course, this table is completely accurate. But the visual appearance of the table subtly misleads the viewer. The table’s layout suggests that each team differs from the team above and the team below by exactly the same degree. It is up to the viewer to compare the numbers in each row to understand the true degrees of difference.
Now consider the same data presented in a tier chart:
National League Central Wins
The tier chart quickly communicates two things. First, it shows that St. Louis, Milwaukee, and Pittsburgh had similar win totals. Second, it illustrates the sizable gap between those three teams and the next team: the Cubs. This is a small demonstration of the value of the tier chart: it provides a quick overview of how the different categories compare to one another. The viewer can then refer to the original table for more details.
Application: fantasy sports data
The tier chart can be particularly useful for fantasy sports owners. In fantasy sports, an owner must be constantly aware of the value of a large number of players. However, it is not absolutely crucial that the owner knows the exact numerical value of each player; for instance, that Arian Foster scores 21 points a game or Calvin Johnson scored 214 points in a season. Instead, the owner must have a solid understanding of how the players compare to one another. “Who is better, Arian Foster or Marshawn Lynch? And how much better is Arian Foster? By a significant margin, or an insignificant one?” In cases like this, where exact values of categories are less important than relative values among categories, the tier chart can be helpful in providing quick and general understanding.
To illustrate this point, here are some tier charts containing fantasy sports-related data. Each chart shows the top 25 players in 2012 for a particular position, and the players are compared according to their total points for the entire year. The points were calculated using standard scoring rules.
Using the tier chart
- Go to the tier chart’s location: http://www.valuebasedgraphing.com/htm/tierchart.html
- In another browser window, open a Google spreadsheet with the data to be loaded into the tier chart. The tier chart expects that there will be a header row, that the first column will contain the categories, and that the second column will contain the sorted values. For an example of proper format, see the National League Central Wins spreadsheet.
- On the browser window displaying the spreadsheet, copy the url out of the Address bar.
- Go back to the browser window displaying the tier chart, and paste the url into the input labeled “Google Spreadsheet Link” and hit the “Load” button.
- Adjust the number in the “Pixels Per Point” spinner. Higher numbers will spread the category units out, while lower numbers will compress them.
- Select a new theme in the “Switch Theme” control to change the appearance of the chart.
Creating links to a tier chart with data
If you have a tier chart loaded with data that you want to share, you can construct a url by combining four strings:
- The url of the google spreadsheet. If the url ends with “#gid=0“, remove those characters from the url.
- The value from the “Pixels Per Point” spinner.
The web page uses css themes from jqueryui.com/.
The control that switches themes was built by Dave Hoff.