Axis

48 posts
The epidemic of simple comparisons

Another day, another Twitter user sent a sloppy chart featured on TV news. This CNN graphic comes from Hugo K. by way of Kevin T. And it's another opportunity to apply the self-sufficiency test. Like before, I removed the data printed on the graphic. In reading this chart, we like to know the number of U.S. reported cases of coronavirus relative to China, and Italy relative to the U.S. So,...

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Comparing chance of death of coronavirus and flu

The COVID-19 charts are proving one thing. When the topic of a dataviz is timely and impactful, readers will study the graphics and ask questions. I've been sent some of these charts lately, and will be featuring them here. A former student saw this chart from Business Insider (link) and didn't like it. My initial reaction was generally positive. It's clear the chart addresses a comparison between death rates of...

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How to read this chart about coronavirus risk

In my just-published Long Read article at DataJournalism.com, I touched upon the subject of "How to Read this Chart". Most data graphics do not come with directions of use because dataviz designers follow certain conventions. We do not need to tell you, for example, that time runs left to right on the horizontal axis (substitute right to left for those living in right-to-left countries). It's when we deviate from the...

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Bubble charts, ratios and proportionality

A recent article in the Wall Street Journal about a challenger to the dominant weedkiller, Roundup, contains a nice selection of graphics. (Dicamba is the up-and-comer.) The change in usage of three brands of weedkillers is rendered as a small-multiples of choropleth maps. This graphic displays geographical and time changes simultaneously. The staircase chart shows weeds have become resistant to Roundup over time. This is considered a weakness in the...

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This Excel chart looks standard but gets everything wrong

The following CNBC chart (link) shows the trend of global car sales by region (or so we think). This type of chart is quite common in finance/business circles, and has the fingerprint of Excel. After examining it, I nominate it for the Hall of Shame. *** The chart has three major components vying for our attention: (1) the stacked columns, (2) the yellow line, and (3) the big red dashed...

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This chart tells you how rich is rich – if you can read it

Via twitter, John B. sent me the following YouGov chart (link) that he finds difficult to read: The title is clear enough: the higher your income, the higher you set the bar. When one then moves from the title to the chart, one gets misdirected. The horizontal axis shows pound values, so the axis naturally maps to "the higher your income". But it doesn't. Those pound values are the "cutoff"...

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How to read this cost-benefit chart, and why it is so confusing

Long-time reader Antonio R. found today's chart hard to follow, and he isn't alone. It took two of us multiple emails and some Web searching before we think we "got it".   Antonio first encountered the chart in a book review (link) of Hal Harvey et. al, Designing Climate Solutions. It addresses the general topic of costs and benefits of various programs to abate CO2 emissions. The reviewer praised the...

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The rule governing which variable to put on which axis, served a la mode

When making a scatter plot, the two variables should not be placed arbitrarily. There is a rule governing this: the outcome variable should be shown on the vertical axis (also called y-axis), and the explanatory variable on the horizontal (or x-) axis. This chart from the archives of the Economist has this reversed: The title of the accompanying article is "Ice Cream and IQ"... In a Trifecta Checkup (link), it's...

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Too much of a good thing

Several of us discussed this data visualization over twitter last week. The dataviz by Aero Data Lab is called “A Bird’s Eye View of Pharmaceutical Research and Development”. There is a separate discussion on STAT News. Here is the top section of the chart: We faced a number of hurdles in understanding this chart as there is so much going on. The size of the shapes is perhaps the first...

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Wayward legend takes sides in a chart of two sides, plus data woes

Reader Chris P. submitted the following graph, found on Axios: From a Trifecta Checkup perspective, the chart has a clear question: are consumers getting what they wanted to read in the news they are reading? Nevertheless, the chart is a visual mess, and the underlying data analytics fail to convince. So, it’s a Type DV chart. (See this overview of the Trifecta Checkup for the taxonomy.) *** The designer did...

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