The Budget Brigade here at OMB Watch clearly loves the budget. We also love pretty visualizations. Sadly, there’s a distinct lack of pretty budget visualizations out there. Lucky for us, into this void has stepped the Data Viz Challenge, which this week announced its winner.

The Challenge was a collaboration between Google, the famous data-hungry behemoth, and Eyebeam, a non-profit that seeks to combine arts and technology. The Challenge used data from WhatWePayFor.com, which takes its data from the presidential budgets archived on the GPO website. Here’s the Challenge itself:

Using data provided by WhatWePayFor.com, we challenge you to create a data visualization that will make it easier for U.S. citizens to understand how the government spends our tax money.

A panel of judges evaluated the projects based on storytelling, clarity, relevance, utility, and aesthetics. In other words, projects had to be useful, as well as imaginative, in showing where your tax dollars go. To make things interesting, the top prize is awarded $5,000, with another $5,000 split among various runners-up.

Some of the resulting entries were a bit strange, but there were a lot of creative ones. One project uses motion-sensing technology to make you physically climb up columns representing agency spending levels. Another shows how your federal taxes were spent in terms of every-day items, like burritos or beers (although I’m not sure how useful it is to know that I gave Medicare the equivalent of 1,305 beers). My personal favorite asks what your favorite government program is, then shows how much of your taxes go to that program, and if you earn more during the year, how much more money you’ll be “contributing” to it through your taxes.

So who won? The winning entry, Where Did My Tax Dollars Go (WDMTDG for short), is half tax receipt, half budget visualization. You simply put in your income and your filing status, and the program goes to work.

First, figures your income taxes, which it breaks down by bracket. This is a pretty neat feature that I haven’t seen before, and helps show how our marginal tax rate system works (even though WDMTDG could explain this feature a bit more). It then calculates your Social Security and Medicare taxes, adds everything together, and gives you an effective tax rate.

But taxes aren’t all Where Did My Tax Dollars Go does. The entire federal budget is shown as a pie chart, with percentages for each budget function (see this site for a description of budget functions). Clicking on a function (health, for instance), brings up its sub-functions (Medicaid grants, NIH funding, children’s health insurance). Each layer also shows how much of your tax dollars go to each function. Admittedly, this isn’t exactly a ground-breaking idea, but WDMTDG makes it all look easy, making you wonder why the 1040 tax form doesn’t include it already. In fact, it’s way better than the taxpayer receipt tool the Administration just released earlier this week, which uses the same data.

Now, WDMTDG isn’t perfect. The tax calculation section on WDMTDG strangely doesn’t include any exemptions in the calculation, meaning the typical person’s numbers probably won’t be accurate (my income taxes were off by 20%).

On the “how it’s spent” side, things aren’t quite right either. Some programs, like Social Security, have dedicated revenue streams, and WDMTDG doesn’t show that. Similarly, WDMTDG ignores all other sources of revenue, like corporate taxes, and doesn’t mention that tax dollars only cover about two-thirds of outlays, with the rest filled in with borrowed money. So your tax dollars don’t really stretch that far.

More importantly, as Tom Lee over at Sunlight Labs pointed out, the Challenge itself is limited in that it only allows entrants to use the WhatWePayFor.com data, which only gives users spending through federal agencies. Specially, Tom notes that this means it doesn’t include tax expenditure data, which leaves out some trillion dollars worth of spending each year. This is a big problem, and as a result, WDMTDG only shows half the picture of how the federal government uses your tax dollars.

I’d go a step further and say the Challenge’s other flaw is WhatWePayFor.com only uses budget authority data, not actual outlays (both are in the President’s Budget). WhatWePayFor.com says this isn’t a big deal, since Congress is usually debating budget authority, so to make Congress more accountable for its actions, you should be looking at budget authority levels. But the problem is budget authority isn’t what is really going out the door. Agencies routinely don’t spend all of their budget authority. This is one of the problems conservative Republicans had with the FY2011 budget compromise: it cut significant amounts of budget authority, but outlays were left relatively unchanged, meaning government spending won’t fall very much as a result of the compromise. For a site called “Where Did My Tax Dollars Go,” it seems odd to not use the figure that shows where your tax dollars go.

Despite these short-comings, WDMTDG is an fun and useful tool. It succeeds at its mission to show, in a digestible way, how your tax dollars are being used, something many Americans need help with. In fact, the entire Challenge is a great idea, and a cheap way to promote creative ways of using government data. Which leaves us with a larger question: why isn’t the federal government running contests like this?