Writing

Updated Salary vs. Performance for 2008

It’s April again, which means that there are messages lurking in my inbox asking about the whereabouts of this year’s Salary vs. Performance project (found in Chapter 5 of the good book). I got around to updating it a few days ago, which means now my inbox has changed to suggestions on how the piece might be improved. (It’s tempting to say, “Hey! Check out the book and the code, you can do anything you’d like with it! It’s more fun that way.” but that’s not really what they’re looking for.)

One of the best messages I’ve received so far is from someone who I strongly suspect is a statistician, who was wishing to see a scatter plot of the data rather than its current representation. Who else would be pining for a scatterplot? There are lots of jokes about the statistically inclined that might cover this situation, but… we’re much too high minded to let things devolve to that (actually, it’s more of a pot-kettle-black situation). If prompted, statisticians usually tell better jokes about themselves anyways.

At any rate, as it’s relevant to the issue of how you choose representations, my response follows:

Sadly, the scatter plot of the same data is actually kinda uninformative, since one of your axes (salary) is more or less fixed all season (might change at the trade deadline, but more or less stays fixed) and it’s just the averages that move about. So in fact if we’re looking for more “accurate”, a time series is gonna be better for our purposes. In an actual analytic piece, for instance, I’d do something very different (which would include multiple years, more detail about the salaries and how they amortize over time, etc).

But even so, making the piece more “correct” misses the intentional simplifications found in it, e.g. it doesn’t matter whether a baseball team was 5% away from winning, it only matters whether they’ve won. At the end of the day, it’s all about the specific rankings, who gets into the playoffs, and who wins those final games. Since the piece isn’t intended as an analytical tool, but something that conveys the idea of salary vs. performance to an audience who by and large cares little about 1) baseball and 2) stats. That’s not to say that it’s about making something zoomy and pretty (and irrelevant), but rather, how do you engage people with the data in a way that teaches them something in the end and gets them thinking about it.

Now to get back to my inbox and the guy who would rather have the data sonified since he thinks this visual thing is just a fad.

Tuesday, April 29, 2008 | examples, represent, salaryper  
Book

Visualizing Data Book CoverVisualizing Data is my book about computational information design. It covers the path from raw data to how we understand it, detailing how to begin with a set of numbers and produce images or software that lets you view and interact with information. Unlike nearly all books in this field, it is a hands-on guide intended for people who want to learn how to actually build a data visualization.

The text was published by O’Reilly in December 2007 and can be found at Amazon and elsewhere. Amazon also has an edition for the Kindle, for people who aren’t into the dead tree thing. (Proceeds from Amazon links found on this page are used to pay my web hosting bill.)

Examples for the book can be found here.

The book covers ideas found in my Ph.D. dissertation, which is basis for Chapter 1. The next chapter is an extremely brief introduction to Processing, which is used for the examples. Next is (chapter 3) is a simple mapping project to place data points on a map of the United States. Of course, the idea is not that lots of people want to visualize data for each of 50 states. Instead, it’s a jumping off point for learning how to lay out data spatially.

The chapters that follow cover six more projects, such as salary vs. performance (Chapter 5), zipdecode (Chapter 6), followed by more advanced topics dealing with trees, treemaps, hierarchies, and recursion (Chapter 7), plus graphs and networks (Chapter 8).

This site is used for follow-up code and writing about related topics.

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