Junk Charts

Welcome

Junk Charts is made by Kaiser Fung, the Web’s first data visualization critic. I discuss what makes graphics work, and how to make them better. Think chartjunk + junk art.

Here is my first post from more than ten years ago. These are the posts with the most (clicks): 1, 2, 3, 4, 5, 6, 7, 8, 9, 10. There are some things I say over and over again: the Trifecta Checkup, the self-sufficiency test, bumps charts, small multiples, the power of aggregation. I carefully tag all posts with topics so clicking on map shows all posts about maps. A list of topics is on the right column. Here is a call for more dataviz criticism.

Here is my other blog, about statistics and Big Data. Here is my twitter feed, aggregating both blogs. If you prefer RSS, there's one feed for Junk Charts, and one for Big Data Plainly Spoken.

I also write popular books about statistics applied to daily life. Here is Numbers Rule Your World, and Numbersense. Tom Peters tweeted: On my 13-hour Boston-Dubai flight, I re-read cover-2-cover Kaiser Fung's superb-useful-fun book Number Sense. Trust him, or trust me.

I am a business statistician and speaker/trainer for hire. This is about a few hours in my life. I built the data teams at Vimeo (still part of the family) and Sirius XM Radio. Click here to write me. Some citations in the media. Talks. A free course.

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Oct 2014: I'm teaching my data visualization workshop. This is a great way for you to learn how to make great graphics in a fun, immersive setting. See a fuller description here.

 

 

Quick example of layering

The New York Times uses layering to place the Alabama tornadoes in context. (link)

Today's wide availability of detailed data allows designers to create dense data graphics like this:

The graphic shows the starting and ending locations and trajectory of each tornado, as well as the wind speeds (shown in color).

Too much data slows down our understanding of the visual message. The remedy is to subtract. Here is a second graphic that focuses only on the strongest tornadoes (graded 4 or 5 on a 5-point scale):

Another goal of the data visualization is to place in context the tornado that hit Beauregard:

The area around Beauregard is not typically visited by strong tornadoes. Also, the tornadoes were strong but there have been stronger ones.

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The designer unfolds the story in three stages. There are no knobs and sliders and arrows, and that's a beauty. It's usually not a good idea to make readers find the story themselves.

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 color coding in science or math class. There is a famous book in our field called The Grammar of Graphics, by Leland Wilkinson, but it’s not a For Dummies book. This void is now filled by Alberto Cairo’s soon-to-appear new book, titled How Charts Lie: Getting Smarter about Visual Information.

As a long-time fan of Cairo’s work, I was given a preview of the book, and I thoroughly enjoyed it and recommend it as an entry point to our vibrant discipline.

In the first few chapters of the book, Cairo describes how to read a chart. Some may feel that there is not much to it but if you’re here at Junk Charts, you probably agree with Cairo’s goal. Indeed, it is easy to mis-read a chart. It’s also easy to miss the subtle and brilliant design decisions when one doesn’t pay close attention. These early chapters cover all the fundamentals to become a wiser consumer of data graphics.

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How Charts Lie will open your eyes to how everyone uses visuals to push agendas. The book is an offshoot of a lecture tour Cairo took during the last year or so, which has drawn large crowds. He collected plenty of examples of politicians and others playing fast and loose with their visual designs. After reading this book, you can’t look at charts with a straight face!

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In the second half of his book, Cairo moves beyond purely visual matters into analytical substance. In particular, I like the example on movie box office from Chapter 4, titled “How Charts Lie by Displaying Insufficient Data”. Visual analytics of box office receipts seems to be a perennial favorite of job-seekers in data-related fields.

The movie data is a great demonstration of why one needs to statistically adjust data. Cairo explains why Marvel’s Blank Panther is not the third highest-grossing film of all time in the U.S., as reported in the media. That is because gross receipts should be inflation-adjusted. A ticket worth $15 today cost $5 some time ago.

This discussion features a nice-looking graphic, which is a staircase chart showing how much time a #1 movie has stayed in the top position until it is replaced by the next higher grossing film.

Cairo’s discussion went further, exploring the number of theaters as a “lurking” variable. For example, Jaws opened in about 400 theaters while Star Wars: The Force Awakens debuted in 10 times as many. A chart showing per-screen inflation-adjusted gross receipts looks much differently from the original chart shown above.

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Another highlight is Cairo’s analysis of the “cone of uncertainty” chart frequently referenced in anticipation of impending hurricanes in Florida.

Cairo and his colleagues have found that “nearly everybody who sees this map reads it wrongly.” The casual reader interprets the “cone” as a sphere of influence, showing which parts of the country will suffer damage from the impending hurricane. In other words, every part of the shaded cone will be impacted to a larger or smaller extent.

That isn’t the designer’s intention! The cone embodies uncertainty, showing which parts of the country has what chance of being hit by the impending hurricane. In the aftermath, the hurricane would have traced one specific path, and that path would have run through the cone if the predictive models were accurate. Most of the shaded cone would have escaped damage.

Even experienced data analysts are likely to mis-read this chart: as Cairo explained, the cone has a “confidence level” of 68% not 95% which is more conventional. Areas outside the cone still has a chance of being hit.

This map clinches the case for why you need to learn how to read charts. And Alberto Cairo, who is a master visual designer himself, is a sure-handed guide for the start of this rewarding journey.

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Here is Alberto introducing his book.

Nice example of visual story-telling in the FT

I came across this older chart in the Financial Times, which is a place to find some nice graphics:

The key to success here is having a good story to tell. Blackpool is an outlier when it comes to improvement in life expectancy since 1993. Its average life expectancy has improved, but the magnitude of improvement lags other areas by quite a margin.

The design then illustrates this story in two ways.

On the right side, one sees Blackpool occupying a lone spot on the left side of the histogram. On the left chart, the gap between Blackpool and the national average is plotted over time. The gap is clearly widening; the size of the gap is labeled so the reader immediately knows it went from 1.8 to 4.9.

Although they're not labeled, the reader understand that the other two lines are the best and worst areas. The comparison between Glasgow City and Blackpool is also informative. Glasgow City, which has the worst life expectancy in the U.K. is fast catching up with Blackpool, the second worst.

I also like color-coded titles. It draws attention to Blackpool and it links the conclusion to both charts in an efficient manner.

Not following direction or order, the dieticians complain

At first glance, this graphic's message seems clear: what proportion of Americans are exceeding or lagging guidelines for consumption of different food groups. Blue for exceeding; orange for lagging. The stacked bars are lined up at the central divider - the point of meeting recommended volumes - to make it easy to compare relative proportions.

The original chart is here, on the Health.gov website.

The little icons illustrating the food groups are cute and unintrusive.

It's when you read further that things start to get complicated. The last three rows display a flipping of the color scheme, with orange on the right, blue on the left. Up to this point, you may understand blue to mean over the recommended value, and orange is under. Suddenly, the orange is shown on the right side.

The designer was wrestling with a structural issue in the data. The last three food groups - sugars, fats and sodium - are things to eat less. So, having long bars on the right side is not good. The orange/blue colors should be interpreted as bad/good and not as under/over.

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The problem with this design is that it draws attention to this color flip - that is to say, it draws attention to which food groups are favored and which ones are to be avoided. This insight is actually in the metadata, not what this dataset is about.

In the following chart, I enforce the bad/good color scheme while ignoring the direction of good. The text is adjusted to use words that do not suggest direction.

Dieticians are probably distressed by this chart, given that most Americans are lagging on almost all of the recommendations.

In a final edit, I re-ordered the categories.