When I saw a demo of the Zillow.com real estate service last month, it struck me as so obvious I wondered why no one had done it before.No doubt. One of our first products, in 1995, was a land records data warehouse. We incorporated assessement, sales, documents and probate information. We also attempted to incorporate GIS tools in a very rudimentary way (this was 1995).Then when Zillow launched on the Web last week, I realized why.
Offering automated property valuations via the Internet turns out to be much harder than it seems -- especially if you expect them to be accurate. But after running extensive tests on this ambitious national real estate service, I found it to be so inaccurate that it's not useful.
The essential problem is that land records and assessment data differs across communities, counties and states. In addition, the data is updated in an often irregular fashion.