Color bomb

I found a snapshot of the following leaderboard (link) in a newsletter in my inbox.

Openrouter_leaderboard_stackedcolumns

This chart ranks different AIs (foundational models) by token usage (which is the unit by which AI companies charge users).

It's a standard stacked column chart, with data aggregated by week. The colors represent different foundational models.

In the original webpage, there is a table printed below, listing the top 20 model names, ordered from the most tokens used.

Openrouter_leaderboard_table

Certain AI models have come and gone (e.g. the yellow and blue ones at the bottom of the chart in the first half). The model in pink has been the front runner through all weeks.

Total usage has been rising, although it might be flattening, which is the point made by the newsletter publisher.

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A curiosity is the gray shaded section on the far right - it represents the projected total token usage for the days that have not yet passed during the current week. This is one of those additions that I like to see more often. If the developer had chosen to plot the raw data and nothing more, then they would have made the same chart except for the gray section. On that chart, the last column should not be compared to any other column as it is the only one that encodes a partial week.

This added gray section addresses the specific question: whether the total token usage for the current week is on pace with prior weeks, or faster or slower. (The accuracy of the projection is a different matter, which I won't discuss.)

This added gray section leaves another set of questions unanswered. The chart suggests that the total token usage is expected to exceed the values for the prior few weeks, at the time it was frozen. We naturally want to know which models are contributing to this projected growth (and which aren't). The current design cannot address this issue because the projected additional usage is aggregated, and not available at the model level.

While it "tops up" the weekly total usage using a projected value, the chart does not show how many days are remaining. That's an important piece of information for interpreting the projection.

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Now, we come to the good part, for those of us who loves details.

A major weakness of these stacked column charts is of course the dizzy set of colors required, one for each model. Some of the shades are so similar it's hard to tell if they repeated colors. Are these two different blues or the same blue?

Openrouter_leaderboard_blues

Besides, the visualization software has a built-in feature that "softens" a color when it is clicked on. This feature introduces unpleasant surprises as that soft shade might have been used for another category.

Openrouter_aimodels_ranking_mutedcolors

It appears that the series is running sideways (following the superimposed gray line) when in fact the first section is a softened red associated with the series that went higher (following the white line).

It's near impossible to work with so many colors. If you extract the underlying data, you find that they show 10 values per day across 24 weeks. Because the AI companies are busy launching new models, the dataset contains 40 unique model names, which imply they needed 40 different shades on this one chart. (Double that to 80 shades if we add the colors on click variations.)

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I hope some of you have noticed something else. Earlier, I mentioned the model in pink as the most popular AI model but if you take a closer look, this pink section actually represents a mostly useless catch-all category called "Others," that presumably aggregates the token usages of a range of less popular models. In this design, the Others category is catching an undeserved amount of attention.

It's unclear how the models are ordered within each column. The developer did not group together different generations of models by the same developer. Anthropic Claude has many entries: Sonnet 4 [green], Sonnet 3.5 [blue], Sonnet 3.5 (self-moderated) [yellow], Sonnet 3.7 (thinking) [pink], Sonnet 3.7 [violet], Sonnet 3.7 (self-moderated) [cyan], etc. The same for OpenAI, Google, etc.

This graphical decision may reflect how users of large language models evaluate performance. Perhaps at this time, there is no brand loyalty, or lock-in effect, and users see all these different models as direct substitutes. Therefore, our attention is focused on the larger number of individual models, rather than the smaller set of AI developers.

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Before ending the post, I must point out that the publisher of this set of rankings offers a platform that allows users to switch between models. They are visualizing their internal data. This means the dataset only describes what customers of Openrouter.ai do on this platform. There should be no expectation that this company's user base is representative of all users of LLMs.


Students demonstrate how analytics underlie strong dataviz

In today's post, I'm delighted to feature work by several students of Ray Vella's data visualization class at NYU. They have been asked to improve the following Economist chart entitled "The Rich Get Richer".

Economist_richgetricher

In my guest lecture to the class, I emphasized the importance of upfront analytics when constructing data visualizations.

One of the key messages is pay attention to definitions. How does the Economist define "rich" and "poor"? (it's not what you think). Instead of using percentiles (e.g. top 1% of the income distribution), they define "rich" as people living in the richest region by average GDP, and "poor" as people living in the poorest region by average GDP. Thus, the "gap" between the rich and the poor is measured by the difference in GDP between the average persons in those two regions.

I don't like this metric at all but we'll just have to accept that that's the data available for the class assignment.

***

Shulin Huang's work is notable in how she clarifies the underlying algebra.

Shulin_rvella_economist_richpoorgap

The middle section classifies the countries into two groups, those with widening vs narrowing gaps. The side panels show the two components of the gap change. The gap change is the sum of the change in the richest region and the change in the poorest region.

If we take the U.S. as an example, the gap increased by 1976 units. This is because the richest region gained 1777 while the poor region lost 199. Germany has a very different experience: the richest region regressed by 2215 while the poorest region improved by 424, leading to the gap narrowing by 2638.

Note how important it is to keep the order of the countries fixed across all three panels. I'm not sure how she decided the order of these countries, which is a small oversight in an otherwise excellent effort.

Shulin's text is very thoughtful throughout. The chart title clearly states "rich regions" rather than "the rich". Take a look at the bottom of the side panels. The label "national AVG" shows that the zero level is the national average. Then, the label "regions pulled further ahead" perfectly captures the positive direction.

Compared to the original, this chart is much more easily understood. The secret is the clarity of thought, the deep understanding of the nature of the data.

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Michael Unger focuses his work on elucidating the indexing strategy employed by the Economist. In the original, each value of regional average GDP is indexed to the national average of the relevant year. A number like 150 means the region has an average GDP for the given year that is 50% higher than the national average. It's tough to explain how such indices work.

Michael's revision goes back to the raw data. He presents them in two panels. On the left, the absolute change over time in the average GDPs are presented for each of the richest/poorest region while on the right, the relative change is shown.

Mungar_rvella_economist_richpoorgap

(Some of the country labels are incorrect. I'll replace with a corrected version when I receive one.)

Presenting both sides is not redundant. In France, for example, the richest region improved by 17K while the poorest region went up by not quite 6K. But 6K on a much lower base represents a much higher proportional jump as the right side shows.

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Related to Michael's work, but even simpler, is Debbie Hsieh's effort.

Debbiehsieh_rayvella_economist_richpoorgap

Debbie reduces the entire exercise to one message - the relative change over time in average GDP between the richest and poorest region in each country. In this simplest presentation, if both columns point up, then both the richest and the poorest region increased their average GDP; if both point down, then both regions suffered GDP drops.

If the GDP increased in the richest region while it decreased in the poorest region, then the gap widened by the most. This is represented by the blue column pointing up and the red column pointing down.

In some countries (e.g. Sweden), the poorest region (orange) got worse while the richest region (blue) improved slightly. In Italy and Spain, both the best and worst regions gained in average GDPs although the richest region attained a greater relative gain.

While Debbie's chart is simpler, it hides something that Michael's work shows more clearly. If both the richest and poorest regions increased GDP by the same percentage amount, the average person in the richest region actually experienced a higher absolute increase because the base of the percentage is higher.

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The numbers across these charts aren't necessarily well aligned. That's actually one of the challenges of this dataset. There are many ways to process the data, and small differences in how each student handles the data lead to differences in the derived values, resulting in differences in the visual effects.


The line-angle illusion

In a recent presentation, Prof. Matthias Schonlau explains his "hammock plot." I wrote about it here. During the talk, he used the hammock plot to illustrate an optical illusion found in plots requiring users to compare angular lines, known as the line-angle illusion. (Others prefer the name "sine" illusion.)

Here is a simple demonstration of the line-angle illusion, extracted from this paper.

Vanderplas_hofmann_sineillusion

Think of the two sine curves as time series, and we're comparing the differences between them. This requires us to assess trend in the vertical distances between the two lines. Weirdly, we perceive the vertical lines on the above chart to have varying lengths, even though they have equal lengths.

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The link here contains an example of how the line-angle illusion can lead to misreading of trends on line charts:

Sineillusion_twolines

Is there a bigger difference in revenue at Time 1 than Time 2? Many of us will think so but on careful judgment, I think all of us can agree that the difference at Time 2 is in fact larger.

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Much of the interest in a hammock plot lies in the links between the vertical blocks, and this is where the line-angle illustion can distort our perception. Studies have shown that humans tend to read not the vertical gaps but the angular gaps. Again, this issue is illustrated in the first mentioned paper:

Vanderplas_hofmann_sineillusion_distances

Matthias explained that their implementation of the hammock plot uses a strategy to counteract this line-angle illusion.

I take this to mean they distort the data in such a way that after readers apply the line-angle illusion, the resulting view would convey correctly the correct trend. A kind of double negative strategy. The paper linked above offers one such counter-illusion strategy.

I imagine this is a bit controversial as we are introducing deliberate distortion to counteract an expected perceptual illusion.

I'm not aware of any software that offers built-in functions that perform this type of illusion-busting adjustments. Do you know any?

 

P.S. [5-30-2025] Andrew Gelman has some comments on this topic on his blog. He said:

But to get closer to what Kaiser is asking: the analogy I’ve given is, suppose you’re building a wooden chair but using boards that are warped. In this case, the right thing to do is to incorporate the warp into the design, i.e. cut some pieces shorter than others and at different angles, etc., so that they fit together as is, rather than trying to go all rectilinear and then glue/nail everything together. The trouble with the latter strategy is that the wood will exert pressure on the joints and eventually the chair will break or distort itself in some way.


Hammock plots

Prof. Matthias Schonlau gave a presentation about "hammock plots" in New York recently.

Here is an example of a hammock plot that shows the progression of different rounds of voting during the 1903 papal conclave. (These are taken at the event and thus a little askew.)

Hammockplot_conclave

The chart shows how Cardinal Sarto beat the early favorite Rampolla during later rounds of voting. The chart traces the movement of votes from one round to the next. The Vatican destroys voting records, and apparently, records were unexpectedly retained for this particular conclave.

The dataset has several features that brings out the strengths of such a plot.

There is a fixed number of votes, and a fixed number of candidates. At each stage, the votes are distributed across the subset of candidates. From stage to stage, the support levels for candidate shift. The chart brings out the evolution of the vote.

From the "marginals", i.e. the stacked columns shown at each time point, we learn the relative strengths of the candidates, as they evolve from vote to vote.

The links between the column blocks display the evolution of support from one vote to the next. We can see which candidate received more votes, as well as where the additional votes came from (or, to whom some voters have drifted).

The data are neatly arranged in successive stages, resulting in discrete time steps.

Because the total number of votes are fixed, the relative sizes of the marginals are nicely constrained.

The chart is made much more readable because of binning. Only the top three candidates are shown individually with all the others combined into a single category. This chart would have been quite a mess if it showed, say, 10 candidates.

How precisely we can show the intra-stage movement depends on how the data records were kept. If we have the votes for each person in each round, then it should be simple to execute the above! If we only have the marginals (the vote distribution by candidate) at each round, then we are forced to make some assumptions about which voters switched their votes. We'd likely have to rule out unlikely scenarios, such as that in which all of the previous voters for candidate X switched to someone other candidates while another set of voters switched their votes to candidate X.

***

Matthias also showed examples of hammock plots applied to different types of datasets.

The following chart displays data from course evaluations. Unlike the conclave example, the variables tied to questions on the survey are neither ordered nor sequential. Therefore, there is no natural sorting available for the vertical axes.

Hammockplot_evals

Time is a highly useful organizing element for this type of charts. Without such an organizing element, the designer manually customizes an order.

The vertical axes correspond to specific questions on the course evaluation. Students are aggregated into groups based on the "profile" of grades given for the whole set of questions. It's quite easy to see that opinions are most aligned on the "workload" question while most of the scores are skewed high.

Missing values are handled by plotting them as a new category at the bottom of each vertical axis.

This example is similar to the conclave example in that each survey response is categorical, one of five values (plus missing). Matthias also showed examples of hammock plots in which some or all of the variables are numeric data.

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Some of you will see some resemblance of the hammock plot with various similar charts, such as the profile chart, the alluvial chart, the parallel coordinates chart, and Sankey diagrams. Matthias discussed all those as well.

Matthias has a book out called "Applied Statistical Learning" (link).

Also, there is a Python package for the hammock plot on github.


Deliberately obstructing chart elements as a plot point

Bbc_globalwarming_ridgeplot smThese "ridge plots" have become quite popular in recent times. The following example, from this BBC report (link), shows the change in global air temperatures over time.

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This chart is in reality a panel of probability density plots, one for each year of the dataset. The years are arranged with the oldest at the top and the most recent at the bottom. You take those plots and squeeze every ounce of the space out, so that each chart overlaps massively with the ones above it.

The plot at the bottom is the only one that can be seen unobstructed.

Overplotting chart elements, deliberately obstructing them, doesn't sound useful. Is there something gained for what's lost?

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The appeal of the ridge plot is the metaphor of ridges, or crests if you see ocean waves. What do these features signify?

The legend at the bottom of the chart gives a hint.

The main metric used to describe global warming is the amount of excess temperature, defined as the temperature relative to a historical average, set as the average temperature during the pre-industrial age. In recent years, the average global temperature is about 1.5 degrees Celsius above the reference level.

One might think that the higher the peak in a given plot, the higher the excess temperature. Not so. The heights of those peaks do not indicate temperatures.

What's the scale of the vertical axis? The labels suggest years, but that's a distractor also. If we consider the panel of non-overlapping probability density charts, the vertical axis should show probability density. In such a panel, the year labels should go to the titles of individual plots. On the ridge plot, the density axes are sacrificed, while the year labels are shifted to the vertical axis.

Admittedly, probability density is not an intuitive concept, so not much is lost by its omission.

The legend appears to suggest that the vertical scale is expressed in number of days so that in any given year, the peak of the curve occurs where the most likely excess temperature is found. But the amount of excess is read from the horizontal axis, not the vertical axis - it is encoded as a displacement in location horizontally away from the historical average. In other words, the height of the peak still doesn't correlate with the magnitude of the excess temperature.

The following set of probability density curves (with made-up data) each has the same average excess temperature of 1.5 degrees. Going from top to bottom, the variability of the excess temperatures increases. The height of the peak decreases accordingly because in a density plot, we require the total area under the curve to be fixed. Thus, the higher the peak, the lower the daily variability of the excess temperature.

Kfung_pdf_variances

A problem with this ridge plot is that it draws our attention to the heights of the peaks, which provide information about a secondary metric.

If we want to find the story that the amount of excess temperature has been increasing over time, we would have to trace a curve through the ridges, which strangely enough is a line that moves top to bottom, initially somewhat vertically, then moving sideways to the right. In a more conventional chart, the line that shows growth over time moves from bottom left to top right.

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The BBC article (link) features several charts. The first one shows how the average excess temperature trends year to year. This is a simple column chart. By supplementing the column chart with the ridge plot, I assume that the designer wants to tell readers that the average annual excess temperature masks daily variability. Therefore, each annual average has been disaggregated into 366 daily averages.

In the column chart, the annual average is compared to the historical average of 50 years. In the ridge plot, the daily average is compared to ... the same historical average of 50 years. That's what the reference line labeled pre-industrial average is saying to me.

It makes more sense to compare the 366 daily averages to 366 daily averages from those 50 years.

But now I've ruined the dataviz because in each probability density plot, there are 366 different reference points. But not really. We just have to think a little more abstractly. These 366 different temperatures are all mapped to the number zero, after adjustment. Thus, they all coincide at the same location on the horizontal axis.

(It's possible that they actually used 366 daily averages as references to construct the ridge plot. I'm guessing not but feel free to comment if you know how these values are computed.)


Election coverage prompts good graphics

The election broadcasts in the U.S. are full-day affairs, and they make a great showcase for interactive graphics.

The election setting is optimal as it demands clear graphics that are instantly digestible. Anything else would have left viewers confused or frustrated.

The analytical concepts conveyed by the talking heads during these broadcasts are quite sophisticated, and they did a wonderful job at it.

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One such concept is the value of comparing statistics against a benchmark (or, even multiple benchmarks). This analytics tactic comes in handy in the 2024 election especially, because both leading candidates are in some sense incumbents. Kamala was part of the Biden ticket in 2020, while Trump competed in both 2016 and 2020 elections.

Msnbc_2024_ga_douglas

In the above screenshot, taken around 11 pm on election night, the MSNBC host (that looks like Steve K.) was searching for Kamala votes because it appeared that she was losing the state of Georgia. The question of the moment: were there enough votes left for her to close the gap?

In the graphic (first numeric column), we were seeing Kamala winning 65% of the votes, against Trump's 34%, in Douglas county in Georgia. At first sight, one would conclude that Kamala did spectacularly well here.

But, is 65% good enough? One can't answer this question without knowing past results. How did Biden-Harris do in the 2020 election when they won the presidency?

The host touched the interactive screen to reveal the second column of numbers, which allows viewers to directly compare the results. At the time of the screenshot, with 94% of the votes counted, Kamala was performing better in this county than they did in 2020 (65% vs 62%). This should help her narrow the gap.

If in 2020, they had also won 65% of the Douglas county votes, then, we should not expect the vote margin to shrink after counting the remaining 6% of votes. This is why the benchmark from 2020 is crucial. (Of course, there is still the possibility that the remaining votes were severely biased in Kamala's favor but that would not be enough, as I'll explain further below.)

All stations used this benchmark; some did not show the two columns side by side, making it harder to do the comparison.

Interesting side note: Douglas county has been rapidly shifting blue in the last two decades. The proportion of whites in the county dropped from 76% to 35% since 2000 (link).

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Though Douglas county was encouraging for Kamala supporters, the vote gap in the state of Georgia at the time was over 130,000 in favor of Trump. The 6% in Douglas represented only about 4,500 votes (= 70,000*0.06/0.94). Even if she won all of them (extremely unlikely), it would be far from enough.

So, the host flipped to Fulton county, the most populous county in Georgia, and also a Democratic stronghold. This is where the battle should be decided.

Msnbc_2024_ga_fulton

Using the same format - an interactive version of a small-multiples arrangement, the host looked at the situation in Fulton. The encouraging sign was that 22% of the votes here had not yet been counted. Moreover, she captured 73% of those votes that had been tallied. This was 10 percentage points better than her performance in Douglas, Ga. So, we know that many more votes were coming in from Fulton, with the vast majority being Democratic.

But that wasn't the full story. We have to compare these statistics to our 2020 benchmark. This comparison revealed that she faced a tough road ahead. That's because Biden-Harris also won 73% of the Fulton votes in 2020. She might not earn additional votes here that could be used to close the state-wide gap.

If the 73% margin held to the end of the count, she would win 90,000 additional votes in Fulton but Trump would win 33,000, so that the state-wide gap should narrow by 57,000 votes. Let's round that up, and say Fulton halved Trump's lead in Georgia. But where else could she claw back the other half?

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From this point, the analytics can follow one of two paths, which should lead to the same conclusion. The first path runs down the list of Georgia counties. The second path goes up a level to a state-wide analysis, similar to what was done in my post on the book blog (link).

Cnn_2024_ga

Around this time, Georgia had counted 4.8 million votes, with another 12% outstanding. So, about 650,000 votes had not been assigned to any candidate. The margin was about 135,000 in Trump's favor, which amounted to 20% of the outstanding votes. But that was 20% on top of her base value of 48% share, meaning she had to claim 68% of all remaining votes. (If in the outstanding votes, she got the same share of 48% as in the already-counted, then she would lose the state with the same vote margin as currently seen, and would lose by even more absolute votes.)

The reason why the situation was more hopeless than it even sounded here is that the 48% base value came from the 2024 votes that had been counted; thus, for example, it included her better-than-benchmark performance in Douglas county. She would have to do even better to close the gap! In Fulton, which has the biggest potential, she was unable to push the vote share above the 2020 level.

That's why in my book blog (link), I suggested that the networks could have called Georgia (and several other swing states) earlier, if they used "numbersense" rather than mathematical impossibility as the criterion.

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Before ending, let's praise the unsung heroes - the data analysts who worked behind the scenes to make these interactive graphics possible.

The graphics require data feeds, which cover a broad scope, from real-time vote tallies to total votes casted, both at the county level and the state level. While the focus is on the two leading candidates, any votes going to other candidates have to be tabulated, even if not displayed. The talking heads don't just want raw vote counts; in order to tell the story of the election, they need some understanding of how many votes are still to be counted, where they are coming from, what's the partisan lean on those votes, how likely is the result going to deviate from past elections, and so on.

All those computations must be automated, but manually checked. The graphics software has to be reliable; the hosts can touch any part of the map to reveal details, and it's not possible to predict all of the user interactions in advance.

Most importantly, things will go wrong unexpectedly during election night so many data analysts were on standby, scrambling to fix issues like breakage of some data feed from some county in some state.


Using disaggregation in dataviz

This chart appears in a journal article on the use of AI (artificial intelligence) in healthcare (link).

Ai_healthcare_barchart

It's a stacked bar chart in which each bar is subdivided into four segments. The authors are interested in the relative frequency of research using AI by disease type. The chart only shows the top 10 disease types.

What is unusual is that the subdivisions are years. So these authors revealed four years of journal articles, and while the overall ranking of the disease types is by the aggregated four-year total counts, each total count has been disaggregated by color so readers can also see the annual counts.

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A slight rearrangement yields the following:

Junkcharts_redo_aihealthcare

Most readers will only care about the left chart showing the total counts. More invested readers may consider the colored charts that show annual totals. These are arranged so that the annual counts are easily read and compared.

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One annoying aspect of this type of presentation is that in almost all cases, the top 10 types in aggregate will not be the top 10 types by individual year. In some of those years, I expect that the 10 types shown do not include all of the top 10 types for a particular year.


Making colors and groups come alive

_numbersense_coverIn the May 2024 issue of Significance, there is an enlightening article (link, paywall) about a new measure of inflation being adopted by the U.K. government known as HCI (Household Costs Indices). This is expected to replace CPI which is the de facto standard measure used around the world. In Chapter 7 of Numbersense (link), I discuss the construction of the CPI, which critics have alleged is manipulated by public officials to be over-optimistic.

The HCI looks promising as it addresses several weaknesses in the CPI measure. First, it implements accounting for household spending on housing - this has always been a tricky subject, regarding those who own homes rather than rent. Second, it recognizes that the average inflation number, which represents the average price changes on the average basket of goods purchased by the average person, does not reflect the experience of many. The HCI measures are broken down into demographic subgroups, so it's possible to compare the HCI of retirees vs non-retirees, for example.

Then comes this multi-colored bar chart:

Sig_hci sm

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The chart is servicable: the reader can find the story. For almost all the subgroups listed, the HCI measure comes in higher than the CPI measure (black). For the income deciles, the reader sense that the relationship is not linear, that is to say, inflation does not increase (or decrease) as income. It appears that inflation is highest at both ends of the spectrum, and lowest for those who are in deciles 6 to 8. The only subgroup for whom CPI overestimates inflation is "private renter," which totally makes sense since the CPI index previously did not account for "owner-occupier housing" cost.

This is a chart with 19 bars, and 19 colors. The colors do not encode any data at all, which is a bit wasteful. We can make the colors come alive by encoding subgroup identity. This is what the grouped bar chart looks like:

Junkcharts_redo_sig_hci_grouped_bars

While this is still messy, this version makes it a bit easier to compare across subgroups. The chart simultaneously plots four different grouping methods: by retired/not, by income deciles, by housing situation and by having children/not. Within each grouping, the segments are mutually exclusive but between the grouping, the segments are overlapping. For example, the same person can be counted in Retired, and having Children, and also some retirees have children while other don't.

***

To better display the interactions between groups and subgroups, I prefer using a dot plot.

Junkcharts_redo_sig_hci_dots

This is not a simple dot plot either. It's a grouped dot plot with four levels that correspond to each grouping method. One can see the distribution of HCI values across the subgroups within each grouping, and also compare the range of values from one group to another group.

One side benefit of using the dot plot is to get rid of the non-informative space between values 0 and 20. When using a bar chart, we have to start the bars at zero to avoid distorting the encoding. Not so for a dot plot.

P.S. In the next iteration, I'd consider flipping the axes as that might simplify labeling the subgroups.

 


The radial is still broken

It's puzzling to me why people like radial charts. Here is a recent set of radial charts that appear in an article in Significance magazine (link to paywall, currently), analyzing NBA basketball data.

Significance radial nba

This example is not as bad as usual (the color scheme notwithstanding) because the story is quite simple.

The analysts divided the data into three time periods: 1980-94, 1995-15, 2016-23. The NBA seasons were summarized using a battery of 15 metrics arranged in a circle. In the first period, all but 3 of the metrics sat much above the average level (indicated by the inner circle). In the second period, all 15 metrics reduced below the average, and the third period is somewhat of a mirror image of the first, which is the main message.

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The puzzle: why prefer this circular arrangement to a rectangular arrangement?

Here is what the same graph looks like in a rectangular arrangement:

Junkcharts_redo_significanceslamdunkstats

One plausible justification for the circular arrangement is if the metrics can be clustered so that nearby metrics are semantically related.

Nevertheless, the same semantics appear in a rectangular arrangement. For example, P3-P3A are three point scores and attempts while P2-P2A are two-pointers. That is a key trend. They are neighborhoods in this arrangement just as they are in the circular arrangement.

So the real advantage is when the metrics have some kind of periodicity, and the wraparound point matters. Or, that the data are indexed to directions so north, east, south, west are meaningful concepts.

If you've found other use cases, feel free to comment below.

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I can't end this post without returning to the colors. If one can take a negative image of the original chart, one should. Notice that the colors that dominate our attention - the yellow background, and the black lines - have no data in them: yellow being the canvass, and black being the gridlines. The data are found in the white polygons.

The other informative element, as one learns from the caption, is the "blue dashed line" that represents the value zero (i.e. average) in the standardized scale. Because the size of the image was small in the print magazine that I was reading, and they selected a dark blue encroaching on black, I had to squint hard to find the blue line.

 

 


One doesn't have to plot raw data

Visual Capitalist chose a treemap to show us where gold is produced (link):

Viscap_gold2023

The treemap is embedded into a brick of gold. Any treemap is difficult to read, mostly because some block are vertical, others horizontal. A rough understanding is nevertheless possible: the entire global production can be roughly divided into four parts: China plus three other Asian producers account for roughly (not quite) a quarter; "rest of the world" (i.e. all countries not individually listed) is a quarter; Russia and Australia together is again a bit less than a quarter.

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When I look at datasets that rank countries by some metric, I'm hoping to present insights, rather than the raw data. Insights typically involve comparing countries, or sets of countries, or one country against a set of countries. So, I made the following chart that includes some of these insights I found in the gold production dataset:

Junkcharts_redo_viscap_gold2023

For example, the top 4 producers in Asia account for almost a quarter of the world's output; Canada, U.S. and Australia together also roughly produce a quarter; the rest of the world has a similar output. In Asia, China's output is about the sum of the next 3 producers, which is about the same as U.S. and Canada, which is about the same as the top 5 in Africa.