46 posts
How to read this chart about coronavirus risk

In my just-published Long Read article at, 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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The unspoken rules of visualization

My latest is at It's an essay on the following observation: The efficiency and multidimensionality of the visual medium arise from a set of conventions and rules, which regularises the communications between producers of data visualisation and its consumers. These conventions and rules are often unspoken: it's the visual equivalent of saying ’it goes without saying’ . There are lots of little things visualization designers do in their sleep...

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What is a bad chart?

In the recent issue of Madolyn Smith’s Conversations with Data newsletter hosted by, she discusses “bad charts,” featuring submissions from several dataviz bloggers, including myself. What is a “bad chart”? Based on this collection of curated "bad charts", it is not easy to nail down “bad-ness”. The common theme is the mismatch between the message intended by the designer and the message received by the reader, a classic error...

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Book Preview: How Charts Lie, by Alberto Cairo

If you’re like me, your first exposure to data visualization was as a consumer. You may have run across a pie chart, or a bar chart, perhaps in a newspaper or a textbook. Thanks to the power of the visual language, you got the message quickly, and moved on. Few of us learned how to create charts from first principles. No one taught us about axes, tick marks, gridlines, or...

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The state of the art of interactive graphics

Scott Klein's team at Propublica published a worthy news application, called "Hell and High Water" (link) I took some time taking in the experience. It's a project that needs room to breathe. The setting is Houston Texas, and the subject is what happens when the next big hurricane hits the region. The reference point was Hurricane Ike and Galveston in 2008. This image shows the depth of flooding at the...

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