Pie chart

135 posts
Pies, bars and self-sufficiency

Andy Cotgreave asked Twitter followers to pick between pie charts and bar charts: The underlying data are proportions of people who say they won't get the coronavirus vaccine. I noticed two somewhat unusual features: the use of pies to show single proportions, and the aspect ratio of the bars (taller than typical). Which version is easier to understand? To answer this question, I like to apply a self-sufficiency test. This...

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Re-engineering #onelesspie

Marco tweeted the following pie chart to me (tip from Danilo), which is perfect since today is Pi Day, and I have to do my #onelesspie duty. This started a few years ago with Xan Gregg. This chart supposedly was published in an engineering journal. I don't have a clue what the question might be that this chart is purportedly answering. Maybe the reason for picking a cellphone? The particular...

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These are the top posts of 2020

It's always very interesting as a writer to look back at a year's of posts and find out which ones were most popular with my readers. Here are the top posts on Junk Charts from 2020: How to read this chart about coronavirus risk This post about a New York Times scatter plot dates from February, a time when many Americans were debating whether Covid-19 was just the flu. Proportions...

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Using comparison to enrich a visual story

Just found this beauty deep in my submission pile (from Howie H.): What's great about this pie chart is the story it's trying to tell. Almost half of the electorate did not vote in Texas in the 2016 Presidential election. The designer successfully draws my attention to the white sector that makes the point. There are a few problems. Showing two decimals is too much precision. The purple sector is...

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Avoid concentric circles

A twitter follower sent me this chart by way of Munich: The logo of the Munich Security Conference (MSC) is quite cute. It looks like an ear. Perhaps that inspired this, em, staggered donut chart. I like to straighten curves out so the donut chart becomes a bar chart: The blue and gray bars mimic the lengths of the arcs in the donut chart. The yellow bars show the relative...

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Bloomberg made me digest these graphics slowly

Ask the experts to name the success metric of good data visualization, and you will receive a dozen answers. The field doesn't have an all-encompassing metric. A useful reference is Andrew Gelman and Antony Urwin (2012) in which they discussed the tradeoff between beautiful and informative, which derives from the familiar tension between art and science. For a while now, I've been intrigued by metrics that measure "effort". Some years...

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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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Everlasting pie chart

Manuel Lima goes into the history of the pie chart, or rather, circle representations in general. Despite many people poo-pooing the chart type over the decades, it keeps hanging around: We might think of the pie chart as a fairly recent invention, with arguably more flaws than benefits, in regards to the statistical portrayal of data. However, if we look deep into history we realize this popular chart is only...

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When the pie chart is more complex than the data

The trading house, Charles Schwab, included the following graphic in a recent article: This graphic is more complicated than the story that it illustrates. The author describes a simple scenario in which an investor divides his investments into stocks, bonds and cash. After a stock crash, the value of the portfolio declines. The graphic is a 3-D pie chart, in which the data are encoded twice, first in the areas...

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Make your color legend better with one simple rule

The pie chart about COVID-19 worries illustrates why we should follow a basic rule of constructing color legends: order the categories in the way you expect readers to encounter them. Here is the chart that I discussed the other day, with the data removed since they are not of concern in this post. (link) First look at the pie chart. Like me, you probably looked at the orange or the...

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