Blog 2020

Mechanical calculators are fascinating. I may have gone down a few rabbit holes on this topic earlier this year, and acquired a few. As a little celebration of the end of this year, and to start the new one, I’m creating a small series of videos about them and releasing one each week.

Line charts – they’re not the most glamorous. And yet, they can be used to tell a compelling story about global warming. In this video, I talk about what I consider a modern classic of data journalism, What’s Really Warming the World by Eric Roston and Blacki Migliozzi: how it works, how it’s structured, and why it works so well.

I covered the more commonly known value index charts in my my last video on index charts, this one is about indexing on the horizontal, or time, axis. It’s kind of fascinating how you can fold the time axis to get a better view of your data. I show how it works and walk through a number of examples, using housing prices, camera sales, global warming, and even data about my running!

To show change over time, you typically use a line chart. But when you’re comparing time series whose values are very different, the differences between the lines can obscure the changes within them. Index charts can help with that. They align values to a reference, or fold the time axis on itself, or even do both.