Zillow is getting a lot of buzz. The site, which provides free estimates of home values, got big writeups yesterday at Cnet and the New York Times as well as a ton of echo coverage in the blogosphere. The company has also scored $32 million in venture financing.
I love the idea of Zillow. Opening up the supply of data about real estate puts a dent in the Realtor cartel, and anything that weakens that price-fixing monopoly is to be welcomed. Zillow’s site itself looks good, too. It assembles all sorts of information on house specs and prices as well as various graphing, mapping, and analysis tools. It is, as Paul Kedrosky writes, “data porn for middle-aged people.”
There’s just one problem. The data’s not reliable. As soon as I got onto the site, I did what I’m sure millions of other people did yesterday: I zillowed my own home. The house description, alas, was way out of date. It didn’t include an addition that we put on three years ago, which meant that the room count, bath count, and square footage were all off. There were also some weird errors. Zillow said, for instance, that the house’s “exterior material” was stucco. I live in Massachusetts, which is not exactly the stucco capital of the world. My house has been clad in shingles since it was built back in the fifties.
If you do some digging at the Zillow site, you’ll find a lot of disclaimers, like this one in all-caps: “ZILLOW.COM PROVIDES THE SERVICES ‘AS IS,’ ‘WITH ALL FAULTS’ AND ‘AS AVAILABLE,’ AND THE ENTIRE RISK AS TO SATISFACTORY QUALITY, PERFORMANCE, ACCURACY, AND EFFORT IS WITH YOU.” There’s also this warning about the quality of the data: “We get this information from the tax assessor in your county so their records may not be up-to-date. To change the details about a home, or the tax value or assessment figure, you’ll need to contact your county assessor’s office.” (To Zillow’s credit, it gives you a personal worksheet where you can tweak the data on your own home, but that’s cumbersome, and it doesn’t help if you’re trying to assess other homes – or if someone else is trying to assess yours.)
The flaws in the data don’t stem from Zillow, but from Zillows’ sources. But users don’t care who’s at fault. They just want accurate, dependable information, particularly if they’re doing something as important and nerve-wracking as buying or selling a house. And the fact that Zillow is just aggregating the data means that it has no way to check or fix the data. The value of its service is at the mercy of its sources.
Zillow’s flaw exposes a deeper problem with the Web 2.0 mashup model. Entrepreneurs are launching all sorts of sites and services that are built on data that they’re siphoning out of third-party sites and databases. Sometimes, the secondhand data is good; sometimes, it’s not. The process of chopping up and bundling data from many different sources can, moreover, amplify inaccuracies. Combine bad data from two different sources and you may get bad data squared. Unfortunately, to the user, the inaccuracies are invisible. The slickness of the interfaces of sites like Zillow, with their tables and graphs and calculators, gives the appearance of credibility, even if it’s not warranted. To use the memorable phrase coined by comedian Stephen Colbert, Web 2.0 sites can all too easily supply “truthiness” rather than truth.
There’s one line of thinking about the unreliability of web information that says, essentially, “get used to it.” People are just going to have to become more sophisticated consumers of information. That’s nice in theory, but it doesn’t wash in the real world. It’s like selling wormy apples and telling customers that they’re just going to have to become more sophisticated eaters of apples. Fruit buyers don’t like worms, and information seekers don’t like bad facts.
The danger is that if users keep coming up against unreliable data they could end up rebelling against the entire mashup model. In Zillow’s case, that would be particularly sad. If the Realtor cartel can use the errors in mashup sites like Zillow to promulgate the message that “you can’t rely on the internet,” such sites could end up reinforcing the status quo rather than breaking it. Truthiness hurts.