Enrico posted about the following chart, addressing the current assault on scientific research funding, and he's worried that poor communications skills are hurting the cause.
He's right. You need half an hour to figure out what's going on here.
Let me write down what I have learned so far.
The designer only cares about eight research areas - all within the IT field - listed across the bottom.
Paired with each named research area are those bolded blue labels that run across the top (but not quite). I think they represent the crowning achievement within each field but I'm just guessing here.
It appears that each field experiences a sequence of development stages. Typically, universities get things going, then industry R&D teams enter the game, and eventually, products appear in the market. The orange, blue and black lines show this progression. The black line morphs into green, and may even expand in thickness - indicating progressive market adoption and growth.
For example, the first field from the left, digital communications, is shown to have begun in 1965 at universities. Then in early 1980s, industry started investing in this area. It was not until the 1990s when products became available, and not until the mid 2000s when the market exceeded $10 billion.
Even now, I haven't resolved all its mysteries. It's not explained the difference between a solid black line and a dotted black line. Further, it appears possible to bypass $1 billion and hit $10 billion right away.
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Next, we must decipher the strange web of gray little arrows.
It appears that the arrows can go from orange to blue, blue to orange, blue to black, orange to black. Under digital communications, I don't see black or green back to blue or orange. However, under computer architecture, I see green to orange; under parallel & distributed systems, I see green to blue. I don't see any black to orange or black to blue, so black is a kind of trapping state (things go in but don't come out). Sometimes, it's better to say which direction is not possible - in this case, I think other than nothing comes out of black, every other direction is possible.
It remains unclear what sort of entity each arrow depicts. Each arrow has a specific start and end time. I'm guessing it has to do with a specific research item. Taking the bottom-most arrow for digital communications, I suppose something begun in academia in 1980 and then attracted industry investment around 1982. An arrow that points backwards from industry to academia indicates that universities pick up new research ideas from industry. Digital communications things tend to have short arrows, suggesting that it takes only a few years to bring a product to market.
To add to this mess, some arrows cross research areas. These are shown as curved arrows, rather than straight arrows. For these curved arrows, the "slope" of the arrow no longer holds any meaning.
The set of gray arrows are trying too hard. They are overstuffed with purposes. On the one hand, the web of arrows - and I'm referring to those between research areas - portray the synergies between different research areas. On the other hand, the arrows within each research area show the development trajectories of anonymized subjects. The arrows going back and forth between the orange and blue bars show the interplay between universities and industry research groups.
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Lastly, we look at those gray text labels at the very top of the page. That's a grab-bag of corporate names (Motorola, Intel, ...) and product names (iPhone, iRobot, ...). Some companies span several research areas. I'm amused and impressed that apparently a linear sequence can be found for the eight research areas such that every single company has investments in only contiguous areas, precluding the need to "leapfrog" certain research areas!
Actually, no, that's wrong. I do notice Nvidia and HP appearing twice. But why is Google not part of digital communications next to iPhone?
Given that no universities are listed, the company and product labels are related to only the blue, black or green lines below. It might be only related to black and/or green. I'm not sure.
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So far, I've expended energy only to tease out the structure of the underlying dataset. I haven't actually learned anything about the data!
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The designer has to make some decisions because the different potential questions that the dataset can address impose conflicting graphical requirements.
If the goal is to surface a general development process that repeats for every research area, then the chart should highlight commonality, rather than difference. By contrast, if one's objective is to illustrate how certain research areas have experiences unique to themselves, one should choose a graphical form that brings out the differences.
If the focus is on larger research areas, then the relevant key dates are really the front ends of each vertical line; nothing else matters. By contrast, if one wants to show individual research items, then many more dates become pertinent.
A linear arrangement of the research areas will not perform if one's goal is to uncover connections between research areas. By contrast, if one attempts to minimize crossovers in a network design, it would be impossible to keep all elements belonging to each research area in close proximity.
A layering approach that involves multiple charts to tell the whole story may be the solution. See for example Gelman's post on ladder of abstraction.