Junk Charts

The less-is-more story, and its meta

The Schwab magazine has an interesting discussion of a marketing research study purportedly showing "less is more" when it comes to consumer choice. They summarized the experimental setup and results in the following succinct graphic:

The data consist of nested proportions. For example, among those seeing display 1, 60% stopped to look at the jams, and among those who stopped, 3% purchased.

The nesting is presented as overlap in this design. The blue figures on pink are those shoppers who stopped as well as purchased. The blue figures with no background are those who stopped but did not purchase. The blue figures disregarding background color include everyone who stopped. What about the gray? Those are the shoppers who did not stop at the jam display, which is not a key number. To understand what proportion of shoppers stopped, the reader must take in the entire set of figures, in effect giving the blue and blue/pink figures a change of clothes.

***

In this version, we make it easier to estimate the proportions:

Each branch starts with 100 figures. The nesting structure is clearly depicted.

***

It turns out that the original design messed up the numbers. They were trying to be precise. The right side (Display 2) had 29 figures on each row, summing to 260, exactly the number of subjects in that treatment cell. The left side had 28 figures per row (one fewer!), summing to 233. However, according to the research paper being cited, they analyzed 242 subjects who saw Display 1. Nine shoppers went missing.

The extra precision, even if correctly rendered, interferes with our comprehension of proportions. Less is more, indeed!

***

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Light entertainment: We're very sorry but this is NOT a pie chart

Someone at YouGov learned an important lesson in what not to do in #dataviz... (Tip from Rob M. via Twitter)

The tweet storm it unleashed was not worth the cute idea.

Here are their tweets:

 

Layered donuts have excess fats and oils

Via Twitter, Nicholas S. sent this chart:

It's a layered donut. There isn't much context here except that the chart comes from USDA. Judging from the design, I surmise that the key message is the change in proportion by food groups between 1970 and 2014. I am assuming that these food groups are exhaustive so that it makes sense to put them in a donut chart, with all pieces adding up to 100%.

The following small-multiples line chart conveys most of the information:

The story is the big jump in "Added fats and oils".  In the layered donut, the designer highlighted this by a moire effect, something to be avoided.

Note the parenthetical 2010 next to the Added fats and oils label. The data for all other food groups come from 2014 but the number for the most important category is four years older. The chart would be more compelling if they used 2010 data for everything.

One piece of information is ostensibly absent in the line chart version - the growth in the size of the pie. The total of the data increased about 20% from 1970 to 2014. In theory, the layered donut can convey this growth by the perimeters of the circles. But it doesn't appear that the designer saw this as an important insight since the total area of the outer donut is clearly more than 20% of the area of the inner donut.

 

A quick lesson in handling more than one messages on one chart

Between teaching two classes, and a seminar, and logging two coast-to-coast flights, I was able to find time to rethink the following chart from the Wall Street Journal: (link to article)

I like the right side of this chart, which helps readers interpret what the alcohol consumption guidelines really mean. When we go out and drink, we order beers, or wine, or drinks - we don't think in terms of grams of alcohol.

The left side is a bit clumsy. The biggest message is that the UK has tightened its guidelines. This message is delivered by having U.K. appear twice in the chart, the only country to repeat. In order to make this clear, the designer highlights the U.K. rows. But the style of highlighting used for the two rows differs, because the current U.K. row has to point to the right side, but not the previous U.K. row. This creates a bit of confusion.

In addition, since the U.K. rows are far apart, figuring out how much the guidelines have changed is more work than desired.

The placement of the bars by gender also doesn't help. A side message is that most countries allow men to drink more than women but the U.K., in revising its guidelines, has followed Netherlands and Guyana in having the same level for both genders.

***

After trying a few ideas, I think the scatter plot works out pretty well. One advantage is that it does not arbitrarily order the data men first, women second as in the original chart. Another advantage is that it shows the male-female balance more clearly.

An afterthought: I should have added the words "Stricter", "Laxer" on the two corners of the chart. This chart shows both the U.K. getting stricter but also that it joins Guyana and Netherlands as countries which treat men and women equally when it comes to drinking.

 

 

Highlights from Milan Expo 2015

You may notice how quiet it is on the blog. That's because I was in Milan last week and spent some memorable time at the EXPO. Here are some highlights as well as tips for those who will be attending.

Over two days, I dropped by 15 or so pavilions and had three meals. Of these, the two most impressive presentations are Vietnam and Austria.

Here is the front of the Vietnam pavilion:

This design is not as elaborate and effusive as some others but it serves its purpose: I was sufficiently attracted to step foot into the building. This is quite an accomplishment, considering that about 140 countries have set up presence along the main route known as the Decumano. In two days, I only saw 10 percent of the exhibitions but I'm really glad I picked Vietnam.

Vietnam basically ignored the theme of the EXPO, which is feeding the planet. Unlike others, I don't think every presentation needs to follow the food theme. It gets boring to see one presentation after another about farming, health and so on. Vietnam decided to offer three concerts a day in which the performers play traditional musical instruments that I haven't encountered before. I was amazed how the stone pieces of this xylophone could be struck to make some very pleasant music:

There were four or five other instruments on display. I stayed for two of them and had to get going. I love the Vietnam presentation because I was entertained and I also learned something new.

On the second day, I came back for some Vietnamese food, which is served at the back of the stage. Go for the summer rolls. If you are into fried foods, the spring rolls and the fried shrimp look like safe bets. The rest of the food didn't appeal to me.

***

The next surprise was Austria. The exterior of Austria's building wasn't that remarkable so it was more of a random choice, perhaps driven by the lack of lines. You may notice a pattern here: I had the best time at the pavilions that are less popular. The most popular ones seem disappointing, and many of them have hour-long waits, even during the day on weekdays, that I did not partake.

The designer of the Austrian presentation noticed the word EAT embedded in BREATHE. They went with a theme about air. They proclaimed that you can live five days without food but only five minutes without air (I don't recall the exact numbers they used but you get the idea). The cynic in me said: nice way to change the subject from food to air! That said, I appreciate that some sites did not find it necessary to follow the theme literally.

They created a world of its own. You are led through a "forest" at the end of which they cool you down with some dry ice. This is a very refreshing experience both mentally and physically. The summer in Milan is hot so you need to cool down once in a while.

In the middle of the route is a small snacks area where they serve traditional Austrian food. My friend and I had some meatballs with deer meat, which is served with some caramelized apple cubes and a creamy celery paste. Those items really did go well together. The apple strudel looked amazing but was a bit overpriced (5 or 6 Euros for a thin slice). If you go to the Austria pavilion, I highly recommend picking up a snack or two.

***

The organizers must be commended for their simple and effective site design. The entire EXPO is laid out along one long main route called the Decumano. It is supremely easy to navigate. It is simply not possible to get lost. It's approximately a 30-minute fast-paced walk end to end.

Also, the entire route is sheltered. I can't emphasize how important this is to keep out the sun (and if you are so unlucky, the rain).

***

Some of the other pavilions that left a good impression:

Pavilion Zero: This is the first building you are supposed to visit before going on the Decumano. A very effective opening statement made by the organizers. Also, some of the rooms showcase great projection technology. Getting out of this building is a bit confusing because you are deposited to the side of the main route, and later I discovered that we had also bypassed the booth where they handed out maps. Just find your way to the main route.

Russia: This is another highlight. They have a quality site. Probably more brainy than some of the others. They serve free Russian sodas, and people were lining up for some free caviar. I would stick to the first floor if you are running out of time. The terrace only holds six people at a time, and there is barely any view.

Belgium: Outside the pavilion, they are serving (standard) Belgian beers and food. A nice sitting area. Inside, they have a chocolate maker but only during certain hours of the day. I'm sad I missed it both days.

Holland: They created a mini theme park with little food trucks serving pancakes, and other goodies. I had a fresh fruit popsicle which looked better on the poster than it tasted. I heard this area gets crowded and fun in the evening. Unlike other countries that showcased "starchitecture," Holland has no real structure and a very brief exhibit.

 ***

Some of my disappointments:

South Korea: This was one of the most highly-rated sites of the EXPO, along with Japan and Kazakhstan. The other two have hour-long waits, plus they have a staged presentation that takes 45 minutes or so, thus I decided to skip them. Korea is said to have an amazing technological display. I saw a computer-programmed music and lights show. It is only a 20 minute experience which flows nicely so I still recommend it. The disappointment came from too high expectations.

Brazil: Probably our biggest mistake. This pavilion is situated almost near the entrance and has a line always. It looked like a lot of fun.They hung up a massive trampoline and people were walking all over it, elevated. Warning: if you are wearing nice shoes, don't get on it. It turns out that you are walking on a grid of thick ropes with netting underneath it. It was very uncomfortable. They also warn you not to jump. You need hard thick soles and big feet. I don't recommend it.

Qatar: This one also got good reviews. I found a lull in the line and waited only 10 minutes or so. They obviously invested in the pavilion. The highlight of the structure is a Guggenheim-style swirling "staircase" to get back to the ground level, with a a movie showing in the middle. You would have to stand there for 10 minutes to figure out what the movie is saying. Not bad but does not merit the hype.

UK: We were lucky to strike up conversation with an attendant who explained the high-minded concept on display here. They have hung a massive metal structure, that was supposed to look like a beehive. According to the attendant, the structure is connected to a real beehive in Nottingham. Lights would switch on and off in Milan based on what the bees are doing back home. Something like that. Sounds interesting from a technological perspective but they didn't do a good job making it real for the person on the street. Their inspiration is that Britain is "a hive of imagination." My friend was asking me if the UK is famous for its bees or honey. I wasn't sure.

***

I have decided to split the post into two. Will also add more pavilion reviews, food reviews, tips, and photos later.

If you are wavering about going to the EXPO, I'd say go!  Enjoy yourself and think of this as the world opening up to you. Some adhere to the theme of feeding the world while others don't. But most of something interesting to say.

[6/24/2015: Added more photos]

Light entertainment on snow day: making light of the meal

Via reader Nick U.

Washington Post featured this here. They apparently understood this graphic:

You could create the same diagram for all the ingredients with overlapping flavor compounds, as in this diagram. There are six that have overlap.  (Again, ignore the math.)

Which six?

There are no easy charts

Every chart, even if the dataset is small, deserves care. Long-time reader zbicyclist submits the following, which illustrates this point well.

The following comments are by zbicyclist:

This is from http://win.niddk.nih.gov/statistics/  -- from the National Institute of Diabetes and Kidney Diseases, part of the U.S. National Institutes of Health.
 
The pie chart is terrible in a pedestrian way – a bar chart could be so much clearer, or even a table. You have to do too much work to match up the colors, numbers and labels on the pie chart.

To the right of the pie is a bar chart, but a bar chart in which the categories are nested – extreme obesity is part of obesity, extreme obesity and obesity are part of overweight or obesity.  If we want to do something like this, there should be 3 charts (e.g. space on the x axis indicating a break). The normal expectation for a bar graph is that the categories are mutually exclusive.  This problem is repeated in the Race/Ethnicity graph just below these.

***

Now, some comments by me.

Another issue of the design is inconsistency. The same color scheme is used in both charts but to connotate different concepts.

Put yourself at the moment when you just understood the chart on the left side. You figured out that obesity is deep green while extreme obesity is light green. Now you shifted your attention to the column chart. You were expecting the light green columns to indicate extreme obesity, and the deep green, obesity. And yet, the light/dark green represents a male-female split.

Here is a stacked column chart showing that females are more likely than males to be either extremely obese or not overweight. In other words, the female distribution has "fatter tails".

I learned the most upsetting thing about this chart when re-making it: the listed percentages on the pie chart added up to 106 percent.

 

Light entertainment: fruits in space

Amusing.

Another example of multiple scales, discussed here.

(via Gelman)

 

Three good charts

Alberto Cairo, Stephen McDaniel and I were asked about our "favorite" data visualization at the Qlik Conference this week. Stephen wrote up our answers here.

Small multiples with simple axes

Jens M., a long-time reader, submits a good graphic! This small-multiples chart (via Quartz) compares the consumption of liquor from selected countries around the world, showing both the level of consumption and the change over time.

What they did right:

• Did not put the data on a map
• Ordered the countries by the most recent data point rather than alphabetically
• Scale labels are found only on outer edge of the chart area, rather than one set per panel
• Only used three labels for the 11 years on the plot
• Did not overdo the vertical scale either

The nicest feature was the XL scale applied only to South Korea. This destroys the small-multiples principle but draws attention to the top left corner, where the designer wants our eyes to go. I would have used smaller fonts throughout.

Having done so much work to simplify the data and expose the patterns, it's time to look at whether we can add some complexity without going overboard. I'd suggest using a different color to draw attention to curves that are strangely shaped -- the Ukraine comes to mind, so does Brazil.

I'd also consider adding the top liquor in each country... the writeup made a big deal out of the fact that most of the drinking in South Korea is of Soju.

***

One way to appreciate the greatness of the chart is to look at alternatives.

Here, the Economist tries the lazy approach of using a map: (link)

For one thing, they have to give up the time dimension.

A variation is a cartogram in which the physical size and shape of countries are mapped to the underlying data. Here's one on Worldmapper (link):

One problem with this transformation is what to do with missing data.

Wikipedia has a better map with variations of one color (link):

The Atlantic realizes that populations are not evenly distributed on the map so instead of coloring countries, thay put bubbles on top of the map (link):

 Unfortunately, they scaled the bubbles to the total consumption rather than the per-capita consumption. You guess it, China gets the biggest bubble and much larger than anywhere else but from a per-capita standpoint, China is behind many other countries depicted on the map.

 

PS. A note on submissions. I welcome submissions, especially if you have a good chart to offer. Please ping me if I don't reply within a few weeks. I may have just missed your email. Also, realize that submissions take even more time to research since it is likely in the area I have little knowledge about, and mostly because you sent it to me since you hope I'll research it. Sometimes I give up since it's taking too much time. If you ping me again, I'll let you know if I'm working on it.

The above does not apply to emails from people who are building traffic for their infographics.

 

PPS. Andrew Gelman chimes in with his take on small multiples.