Chart of the Week: Visualizing Multi-​select survey questions

Visu­al­iz­ing multi-​select sur­vey ques­tions (where the respon­dents can pro­vide mul­ti­ple answers) is chal­leng­ing to sum­ma­rize since pie charts and 100% bar charts do not work well since the parts can add up to be more than 100%. In the book Pic­tur­ing the Uncer­tain World: How to Under­stand,
Com­mu­ni­cate, and Con­trol Uncer­tainty through Graph­i­cal Dis­play
, the author gives the exam­ple of a sur­vey of ser­mon top­ics, and uses a vari­ant of Nightin­gale– rose (also called a polar area chart or “cox­comb”) to dis­play the sur­vey results:

Visualization using a modified polar area diagram in H. Wainer's Understanding Unvertainty.

Visu­al­iza­tion using a mod­i­fied polar area dia­gram in H. Wainer’s Under­stand­ing Unvertainty.

The author, Howard Wainer, com­ments that this chart has a flaw — while the length of the fil­a­ments is pro­por­tional to the size, there’s an impli­ca­tion that the reader is inter­pret­ing it as an area chart (as would be in the Nightin­gale rose which would use solid shapes, rather than fil­a­ments). Here each data point uses 9 fil­a­ments of vary­ing lengths. Here’s an alter­na­tive way to visu­al­ize the infor­ma­tion using a sim­ple bar chart:

Bar chart of sermon topics

Bar chart of ser­mon topics

Finally, a matrix view. Since I didn’t have the orig­i­nal data, I added 10 groups of respon­dents and also rounded to the near­est 10%. The rows con­tan the same data points as the orig­i­nal, but the columns show, for exam­ple, a group A which only preaches on two of the top­ics, while group B preaches on seven /​10 top­ics. These lend them­selves to addi­tional group­ing and insight. Per­haps goups B and C empha­size more social issues in their ser­mons, while group A focuses on other types of top­ics. This matrix view is more infor­ma­tion dense (presents more data) and can yield more insights depend­ing on the survey.wainer2

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