#ThrowbackThursday
In my part-time job as a Data Analytics Mentor at Fullstack Academy, I enjoy offering feedback and challenging students in their data visualizations. A student reviewed his capstone project’s data visualizations with me and this was one of them:
I told him his use of color was confusing and asked what he wanted to convey. He wanted to display two average baseball metrics of each baseball player. (I’m sorry, I don’t remember the metrics as a non-sports person.) I first suggested a side-by-side bar graph.
It was easier to read, but is there a better way to visualize this data? I then suggested a butterfly chart. (At this point in time, I have never made one before, but I have seen them before.) He took my suggestion and returned to me later that afternoon with much clearer visualizations!
In honor of his improvement, I learned how to make a butterfly chart:
1. Create a bar chart with your measures in the columns and dimension in the rows. In this case, I used ISO (Isolated Power, which is a measure of a hitter's raw power) and SLG (slugging percentage, which is a measure of the batting productivity of a hitter) for my measures and Name (of baseball players) as my dimension.
2. Right-click the left axis and select Edit Axis. In the dialogue box, select Reversed.
3. Create a calculated field. I like to do this by selecting the drop down menu in the Data pane.
4. Create a calculated field called Zero Line with the value of 0.
5. Drag the new Zero Line measure into the Columns shelf, between the two present measures.
6. Add your dimension, in this case Name, into Label in the SUM(Zero Line) marks card.
7. Center the label in Alignment.
8. Change the mark type to Text.
9. Right-click the Zero Line axis and Edit Axis. In this dialogue box, remove the text “Zero Line” in Title.
10. In the same dialogue box, in the Tick Marks tab, under Major Tick Marks, select None.
11. From here, remove chart junk and stylize your butterfly chart to your liking.
My student’s data visualization looked a little different from what I recreated, but learning how to create a butterfly chart may be useful to both of us in the future.
Unfortunately, if you do not like the spacing between the text in the middle and bars, you would have to create the butterfly chart visualization in 3 worksheets, like I have done in this Makeover Monday:
