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Good Visualization

Image:A1-CA-copper.gif Image:A1-CA-gallium.gif Image:A1-CA-hafnium.gif Image:A1-CA-indium.gif Image:A1-CA-tantalum.gif Image:A1-CA-tin.gif


Samuel K. Moore. Supply Risk, Scarcity, and Cellphones. IEEE Spectrum. March 2008, pg. 76. [Online]


This series of charts and graphs (which can be viewed online; the print article is of superior quality) provides a visualization of cost, production, and importance of the different kinds of rare materials used in cellphones. The left hand column provides a few snippets of key information (where the material is used, produced, and notes on scarcity). The rest of the columns visualize historical trends in prices and production and the reserve base, all somewhat relative to each other for easy comparison.

In addition to the uniform layout, the choices of colors and graphs help separate the categories in a pleasing way. It could have certainly been made worse by attempting to put all the prices of the different materials on one graph. It's a bit unfortunate that some of the data is missing; but the point the author is trying to make is clearly conveyed.


This full-page visualization consists of 4 figures/graphs of 6 different materials, for a total of 24 individual figures. Because some of the data is unavailable, we only have 19. Overall, the layout of the page is clean and uniform. On the first column, we have nominal data: the element of choice. Entries are separated by a horizontal rule and each entry's corresponding graph are all located on the same column for easy comparison. The color of the graphs are assigned to nominal (N) types; in this case we have Green: price per kilogram vs. year, Yellow: World production vs. year, Orange/Red: Importance in use vs. Supply Risk, Blue: Reserve base (as of 2006/07).

In general, the graphs and charts are simple and are labeled with the essential information; units are clearly labeled, but precise numbers aren't listed or given in a chart. Some of the graphs and the text is a bit small (presumably due to limited print space) but legible.

  • Price per kilogram: The x-axis is the year (Q), with the y-axis being the price per kilogram in US $. The graph is somewhat misleading, as the lines connected between two points don't necessarily have a relationship. Each data point is the annual average, so this could have been better off as a scatter plot. If a monthly or daily price was being visualized, the graph may have shown more fluctuation; in general, however, the idea is being conveyed that prices are increasing per kg. It would have been more helpful if the relative increase in price were shown.
  • World production: On the x-axis is the year (Q) with the y-axis representing world production. It's a bit unclear whether the lines connected between the two points mean anything, other than to emphasize a particular trend.
  • Importance in use vs. Supply risk: on the x-axis is a scale from 0.0-4.0 that is consistent for each element, and attempts to show how important an element is and the supply risk. Although not stated, presumably a 4 means most important or highest risk, with a 0 being least important or least supply risk.
  • Reserve base: This figure shows the current reserve base of the material in metric tons. We learned that a two-dimensional area graphic isn't a good visualization for 1 dimensional data. In this case, the larger the circle, the greater the reserve base relative to other materials. The lie factor, however, would be too small to accurately represent the relative sizes of the reserve bases.

Bad Visualization



James F. Kurose, Keith W. Ross. Computer Networking: A Top-Down approach. 4th ed. Pearson Education. Figure 2.26.


This image comes from a textbook used in EE122: Computer Networks and attempts to convey the distributed nature of file distribution in the BitTorrent protocol. Although the general concept of the distributed nature of BitTorrent is conveyed, it does so in an almost vague and unclear manner to those unfamiliar with the protocol.

One could deduce, by the bolded arrows on the left-hand side that Alice must first download a list of peers from the tracker, and then "trades chunks" with the peers parsed from the downloaded list. It would have been a simple addition of a numeral to state the steps Alice takes in order to download a file. Also, is Alice is constant communication with the tracker to get updated lists of peers (as they come and go) or is the peer download a one time event? This isn't described in the figure.

The majority of the diagram is even more vague; peers are apparently trading chunks with Alice and amongst themselves, but a clear idea of what a chunk or how they are traded isn't conveyed in the figure. Perhaps after reading the corresponding text, readers can get a sense of what is supposed to happen, but the figure doesn't explain it well. Certain aspects of the protocol, like partial file sharing or the communication of how to figure out what chunks to download are not described as well.


This visualization is a very simple graph or network and consists of nominal data. In particular, we see that Alice is on a computer in an imaginary "cloud" of other peers or systems. The lines connecting Alice to the Tracker, Alice to the Peer, and other Peer to Peers aren't defined in the figure, but one can infer that a path across the network over n hops is established between two points.

The bold blue line on the left-hand side signifies that for Alice to communicate with any peers to establish a connection and exchange data, she needs to first speak with the Tracker and obtain a list of peers. It is again unclear what the arrowheads at each endpoint means; presumably data is being sent and received from both points. Although Alice has received a list of peers, she is not communicating with all of them. Is there any reason why? In addition, none of the peers seem to have any connections with the Tracker; does this mean Alice eventually disconnects from the Tracker and stops all communication? If we presume that the visualization is through Alice's perspective, then how do we know that the other peer's are connected with each other, unless they announce it to the rest of the peers? There is a lot of ambiguity and missing information with this figure.

Also, the notion or process of how files are distributed across the network is unclear. Peers are trading chunks, but there is no visual display or notion of what a "chunk" is or how to determine which chunks are being sent. It's a mystery as to what exactly is being communicated between each of the peers. A glance at the image reveals to the reader that BitTorrent is a method of file distribution by offloading the work across various peers, but that is as far as the figure goes in explaining BitTorrent.


The redesign proved to be more challenging than expected; I wanted to convey the distributed nature of the file sharing, but designing it from the perspective of Alice made some of the labeling a bit confusing. Since most of the variables were nominal, I made heavy use of positioning and colors to convey some of the concepts of BitTorrent. For example, Alice connects only to a few peers and attempts to download and share with others as much as possible before moving on. At the same time, however, file exchange is taking place throughout the swarm, as well.

The use of progress bars, for example, adds more detail about the nature of BitTorrent. Not all clients connected to the swarm have the complete file, but are sharing what they have and downloading what they don't have. It also establishes the notion that these "chunks" being traded aren't necessarily in sequential order.

Perhaps the most difficult part of this redesign was not trying to fill the image up with text and letting the visualization do the explaining. At the same time, since this is a visualization of a concept/protocol, it's quite difficult to present a simple visualization without any corresponding text/explanation for fear of ambiguity or lack of clarity (see previous image).


Megan Jaegerman's brilliant news graphics

I found this earlier this summer about Megan Jaegerman, who designed many news graphics for The New York Times from 1990-1998. A lot of fascinating and very informative images.

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