Complex Diagrams

Electoral-Vote.com is an excellent and popular site for tracking polls for president on a state by state basis. One of the nice features is a historical graph that shows the changing number of electoral votes for each candidate over the election season.

Currently it looks something like this:

(click to see the original on electoral-vote.com)

Just for fun, I decided to see what it would look like showing the candidate totals as a single shared line. (This is similar to the epic graph representing the Senate History Timeline.)

In the revised version, the vertical axis counts votes for Obama going upward, as in the original, and votes for McCain going downward. The axis labels are color coded to reflect the candidate they represent. The color of the line reflects the candidate with more votes for that time period.

Theoretically, when the votes total line is above the 271 line, Obama is ahead; when it’s below the 271 line, McCain is ahead. However, the revision isn’t perfect, and accuracy suffers relative to the original in a few ways.

• In situations where a state (such as Florida) is tied, neither candidate is credited with the votes, so the total number fluctuates. This is not handled well in the revision.

• It’s a little trickier to represent the situation when the count is very near 270 (see late April and early May in the original).
• Because the total number of electoral votes is 538, it’s impossible to use round numbers at both ends of the shared grid lines.

While not a superior solution overall, the revised version does have some merit. As a rough tool for observing trends, I think a single line is cleaner, easier to follow, and the changing colors are a little easier to tell a story with.

Should you be required to work in Visio, you may well find yourself, as I did, wishing to measure your drawing in pixels. I couldn’t figure out how do do it, though Visio does support such diverse measurements as Ciceros and Didots.

I finally found the definitive answer from Microsoft: For some types of drawings, you may want to change the measurement units to pixels. However, a pixel isn’t a unit of measurement. A pixel is just a dot on a screen and the size of the dot varies for different screens. To simulate pixels, set the measurement units to points.

Needless to say, this is not satisfying. It’s true a pixel is only an on-screen measure, and is clearly only useful for a few, obscure situations, such as when creating interface mockups, wireframes, or prototypes for software, the web, or any other sort of images meant to be viewed on a screen.

Luckily, Visio provides a set of features that allow a fairly simple, two step work-around. Warning: doing this on existing Visio documents may severely distort your existing drawings. I suggest working on duplicate files, not originals.

Step One Open the File > Page Setup menu and select the Page Properties tab. In the Measurement units field select Picas.

Step Two In the same dialog box, select the Drawing Scale tab. Select the Custom Scale radio button and set the ratio to 1 p = 16 p.

That’s it. Click OK and you’re all set to go.

Why it works Picas are 6 to the inch. By setting the ratio at 1:16, Visio presents a diagram at 96 picas per inch, the same as the Windows standard of 96 pixels per inch. You could set an appropriate ratio with any of the available units, but it works well with picas, and I find it useful that all units are labeled as p.

Here is a Visio file template with the units set properly.

Zillow has posted a series of excellent diagrams which show relative changes in assorted housing markets, broken down by segment. Their diagrams are very clear and allow fairly quick access to a lot of good information. Please go explore there, and then come back here for my commentary.

By my count, there are eight different axes of information represented for each city or market:

1. lower bound of each market
2. upper bound of each market
3. overall span of each market
4. lower bound of each segment
5. upper bound of each segment
6. overall span of each segment
7. direction of change for each segment
8. magnitude of change for each segment

The first six of these axes are a natural byproduct of using the (horizontal) stacked bar chart format that they’ve chosen. Given how bad bar charts typically are (N.B. Excel), they did a great job with the shapes, colors, and generally minimalist approach. They’re really quite good.

To fully optimize the diagrams, I’d make a few minor changes.

Sorting the markets alphabetically makes it easy to find specific markets by name, but difficult to compare them. Regional groupings might be more useful. In an ideal world, the user could select a few markets by name and compare just those selected few.

The weakest point, in my opinion, is the ambiguity introduced by the arrows. I understand that they are meant to represent trends, not specific quantities. However, they can easily be made a little more clear.

Judging from the legend, the length of the shaft of the arrow represents the actual quantity, while the head encodes direction (redundantly with position and color). In some cases, such as our hometown of Seattle, the heads are ponderously large compared to the length of the shaft, making anything more than a cursory comparison impossible.

Removing the heads and using rectangular bars would make it easier to compare values at a glance. If we wanted to get more specific, the percent change per segment could be displayed within the segment oval, in red or green text.

While not quite as dramatic, I think these changes make the diagram more useful, without reducing their accessibility.

Finally, and this is a minor point, the legend states that “the top and bottom groups have been cut for better visualization.” This is entirely reasonable, but it made me curious about where they chose to trim those groupings. It would be nice to know what fraction of the actual number of homes are represented in the high- and low-end bars.

I was just introduced to the Song Chart group group on Flickr. It’s full of visualizations of song lyrics. Many are clever, many are hilarious. This is my contribution.

Here’s a podcast/webinar of me being interviewed by Tom Crawford, who runs the VizThink conference. He asked some good questions. It was a lot of fun.

There’s a video version showing the example diagrams, as well as an audio-only version.

The public presentation of a speech (when unsupported by visual aids) is an interesting form of discourse because it contains little-to-no explicit structure. Typically, a speech is delivered (or read) with very few indications of structure presented to the listener (or reader). Because they are designed to be spoken aloud and heard, there are no chapter titles or section headings in the text. At best, the speaker may pause to indicate a change of topic, or reveal a bit of structure by saying “now I’m going to talk about,” or, “let me give you an example.”

However, there is structure present in a speech. The speaker must present evidence or examples to support their goals, whether their goals are to persuade, inform, or entertain. They may also draw conclusions, ask relevant questions, or predict, all based on their evidence and conclusions. In order for the speech to be successful, the evidence, conclusions, and predictions must be logically tied together to build a coherent argument. In a well-crafted speech, the audience will have no trouble following the thread of the argument, despite the lack of explicit structure. However, if there is more than a small amount of content in the speech, the audience may not have the ability to rank the importance of various ideas, or even to identify the key concepts.

This is a diagram I created of the first half of the speech Viva Las Xmas [PDF, HTML] by Larry Harvey (2002), the founder of the Burning Man project. In the speech, he discusses some socioeconomic principles, and how they affect interactions between people in a marketplace economy, and also in the gift economy at Burning Man. The diagram uses placement, color, and links to show not only the chronology, hierarchical, and topical groupings of chunks of the speech, but also causality and conceptual connections among the chunks.

This has some significant consequences. Not only does the diagram immediately reveal the topical threads in the speech, it also makes the important concepts clear by virtue of their relatively high number of links to other portions of the speech. The connections, relationships, and implications that are implicit in the speech become explicit in the diagram, thereby conveying more complete knowledge to the reader, reducing the amount of raw information that they have to integrate, and making the actual message of the speech more accessible. This type of diagram could be constructed before the presentation of a speech, and then used to support the speech as it was being delivered. This would enable the speech author to emphasize the key points and make the speech easier to follow. This diagram reveals six dimensions of complexity.

1. hierarchical membership, indicated by the horizontal position below the green boxes and redundantly encoded with the vertical black arrows
2. topical grouping, indicated by the vertical position and redundantly encoded by color
3. specific chunk, indicated by the text in each box
4. chronological sequence, indicated by relative left to right position
5. causality, indicated by red arrows
6. conceptual connection, indicated by green arrows

I created this diagram in the fall of 2003. The diagram and the text of this post appear in my thesis.

This diagram has been arranged to show not only the hierarchy, but also the intended use pattern of a typical, linear, non-fiction book.

• Continuity in the book is indicated by contact of the circles.
• The gray line, progressing in small and large clockwise arcs from section to section and chapter to chapter, demonstrates the linear progression of the content.
• The dashed black arrows show some possible non-linear paths that may be traveled by the reader to view content that is not part of the main linear flow of the book.

The goal of displaying the use of the book, and not merely the hierarchy, has led to an atypical diagram that conveys more knowledge than the typical counterpart.

I created this diagram in the fall of 2003. It appears in my thesis, and was selected to be supporting material for the book The Practical Guide to Information Design, by Ronnie Lipton.

My master’s thesis is a system for creating good diagrams. It starts with the basics of perception and cognition, and walks the reader through the process of making appropriate choices for their particular design problem.

[download page: 10MB PDF]

From the abstract:
This thesis presents a system for the generation of complex diagrams. “Complexity” is defined as a measure of distinct data types that are independently visually encoded. Diagrams representing four or more types of data are defined as complex, while diagrams representing three or fewer are simple. Successful generation of complex diagrams is dependent on appropriate design choices. Five fundamental principles are introduced to guide the choices made by the diagram designer. The two contextual fundamental principles are “different goals require different methods,” addressing the needs of the diagram designer, and “audience brings context with them,” addressing the needs and context of the diagram reader. The three perceptual fundamental principles are the “principle of information availability,” which guides the selection and density of the diagram elements, the “principle of semantic distance,” which guides the spatial placement and grouping of the diagram elements, and the “principle of informative changes,” which guides the visual encoding of the diagram elements. A review of the diagram design process, comprising selection, encoding, and placement of the diagram components, is given. For each phase of the design process the influence of the appropriate fundamental principles is discussed, and the fundamental principles are extended into applied guidelines and suggestions.