Medicine

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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Probabilities and proportions: which one is the chart showing

The New York Times showed this chart (link): My first read: oh my gosh, 40-50% of the unvaccinated Americans are living their normal lives - dining at restaurants, assembling with more than 10 people, going to religious gatherings. After reading the text around this chart, I realize I have misinterpreted it. The chart should be read by columns. Each column is a "pie chart". For example, the first column shows...

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The time has arrived for cumulative charts

Long-time reader Scott S. asked me about this Washington Post chart that shows the disappearance of pediatric flu deaths in the U.S. this season: The dataset behind this chart is highly favorable to the designer, because the signal in the data is so strong. This is a good chart. The key point is shown clearly right at the top, with an informative title. Gridlines are very restrained. I'd draw attention...

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Same data + same chart form  = same story. Maybe.

We love charts that tell stories. Some people believe that if they situate the data in the right chart form, the stories reveal themselves. Some people believe for a given dataset, there exists a best chart form that brings out the story. An implication of these beliefs is that the story is immutable, given the dataset and the chart form. If you use the Trifecta Checkup, you already know I...

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Making graphics last over time

Yesterday, I analyzed the data visualization by the White House showing the progress of U.S. Covid-19 vaccinations. Here is the chart. John who tweeted this at me, saying "please get a better data viz". I'm happy to work with them or the CDC on better dataviz. Here's an example of what I do. Obviously, I'm using made-up data here and this is a sketch. I want to design a chart...

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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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Illustrating differential growth rates

Reader Mirko was concerned about a video published in Germany that shows why the new coronavirus variant is dangerous. He helpfully provided a summary of the transcript: The South African and the British mutations of the SARS-COV-2 virus are spreading faster than the original virus. On average, one infected person infects more people than before. Researchers believe the new variant is 50 to 70 % more transmissible. Here are two...

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A beautiful curve and its deadly misinterpretation

When the preliminary analyses of their Phase 3 trials came out , vaccine developers pleased their audience of scientists with the following data graphic: The above was lifted out of the FDA briefing document for the Pfizer / Biontech vaccine. Some commentators have honed in on the blue line for the vaccinated arm of the Pfizer trial. Since the vertical axis shows cumulative number of cases, it is noted that...

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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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Putting vaccine trials in boxes

Bloomberg Businessweek has a special edition about vaccines, and I found this chart on the print edition: The chart's got a lot of white space. Its structure is a series of simple "treemaps," one for each type of vaccine. Though simple, such a chart burns a few brain cells. Here, I've extracted the largest block, which corresponds to vaccines that work with the virus's RNA/DNA. I applied a self-sufficiency test,...

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