Comparability

31 posts
Hanging things on your charts

The Financial Times published the following chart that shows the rollout of vaccines in the U.K. (I can't find the online link to the article. The article is titled "AstraZeneca and Oxford face setbacks and success as battle enters next phase", May 29/30 2021.) This chart form is known as a "streamgraph", and it is a stacked area chart in disguise.  The same trick can be applied to a column...

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Did prices go up or down? Depends on how one looks at the data

The U.S. media have been flooded with reports of runaway inflation recently, and it's refreshing to see a nice article in the Wall Street Journal that takes a second look at the data. Because as my readers know, raw data can be incredibly deceptive. Inflation typically describes the change in price level relative to the prior year. The month-on-month change in price levels is a simple seasonal adjustment used to...

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Circular areas offer misleading cues of their underlying data

John M. pointed me on Twitter to this chart about the progress of U.S.'s vaccination campaign: This looks like a White House production, retweeted by WHO. John is unhappy about this nested bubble format, which I'll come back to later. Let's zoom in on what matters: An even bigger problem with this chart is the Q corner in our Trifecta Checkup. What is the question they are trying to address?...

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Handling partial data on graphics

Last week, I posted on the book blog a piece about excess deaths and accelerated deaths (link). That whole piece is about how certain types of analysis have to be executed at certain moments of time.  The same analysis done at the wrong time yields the wrong conclusions. Here is a good example of what I'm talking about. This is a graph of U.S. monthly deaths from Covid-19 during the...

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Dreamy Hawaii

I really enjoyed this visual story by ProPublica and Honolulu Star-Advertiser about the plight of beaches in Hawaii (link). The story begins with a beautiful invitation: This design reminds me of Vimeo's old home page. (It no longer looks like this today but this screenshot came from when I was the data guy there.) In both cases, the images are not static but moving. The tour de force of this...

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Convincing charts showing containment measures work

The disorganized nature of U.S.'s response to the coronavirus pandemic has created a sort of natural experiment that allows data journalists to explore important scientific questions, such as the impact of containment measures on cases and hospitalizations. This New York Times article represents the best of such work. The key finding of the analysis is beautifully captured by this set of scatter plots: Each dot is a state. The cases...

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Making better pie charts if you must

I saw this chart on an NYU marketing twitter account: The graphical design is not easy on our eyes. It's just hard to read for various reasons. The headline sounds like a subject line from an email. The subheaders are long, and differ only by a single word. Even if one prefers pie charts, they can be improved by following a few guidelines. First, start the first sector at the...

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Why you should expunge the defaults from Excel or (insert your favorite graphing program)

Yesterday, I posted the following chart in the post about Cornell's Covid-19 case rate after re-opening for in-person instruction. This is an edited version of the chart used in Peter Frazier's presentation. The original chart carries with it the burden of Excel defaults. What did I change and why? I switched away from the default color scheme, which ignores the relationships between the two lines. In particular, the key comparison...

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Election visual 3: a strange, mash-up visualization

Continuing our review of FiveThirtyEight's election forecasting model visualization (link), I now look at their headline data visualization. (The previous posts in this series are here, and here.) It's a set of 22 maps, each showing one election scenario, with one candidate winning. What chart form is this? Small multiples may come to mind. A small-multiples chart is a grid in which every component graphic has the same form -...

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Ask how you can give

A reader and colleague was frustrated with the following graphic that appeared in the otherwise commendable article in National Geographic (link). The NatGeo article provides a history lesson on past pandemics that killed millions. What does the design want to convey to readers? Our attention is drawn to the larger objects, the red triangle on the left or the green triangle on the right. Regarding the red triangle, we learn...

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