Content for Tuesday, May 26, 2020


Questions to reflect on

  • When is it okay (or not) to truncate the y-axis?
  • It is remarkably easy to mislead people with many of these chart types. Why? How can you avoid the same mistakes?
  • All these types of charts are good at communicating change over time, but some are more appropriate in different situations. When is it best to use these different types (e.g. line graphs vs. area graphs vs. horizon charts vs. heatmaps, etc.)?


The slides for today’s lesson are available online as an HTML file. Use the buttons below to open the slides either as an interactive website or as a static PDF (for printing or storing for later). You can also click in the slides below and navigate through them with your left and right arrow keys.

View all slides in new window Download PDF of all slides

Fun fact: If you type ? (or shift + /) while going through the slides, you can see a list of special slide-specific commands.


Videos for each section of the lecture are available at this YouTube playlist.

You can also watch the playlist (and skip around to different sections) here:

  1. Alberto Cairo, The Truthful Art: Data, Charts, and Maps for Communication (Berkeley, California: New Riders, 2016).↩︎

  2. Zan Armstrong and Martin Wattenberg, “Visualizing Statistical Mix Effects and Simpson’s Paradox,” in Proceedings of IEEE InfoVis 2014, 2014, https://research.google.com/pubs/pub42901.html.↩︎