Real Estate Site Boasts Data on Nearly 90% of all U.S. homes

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RISMEDIA, Jan. 11, 2008-Real estate Web site Zillow.com announced a major expansion and upgrade to its database of nearly all homes in the country — increasing data coverage from 70 million to 80 million U.S. homes in 48 states, or 88% of all homes in the country(1). Zestimate values are now available on three out of four U.S. homes, or 67 million, up 68% from when Zillow launched in 2006. New areas with Zestimates include the states of Alabama, Arkansas, Delaware, Iowa, Idaho, Indiana, Kansas, Kentucky, Louisiana, West Virginia and New Hampshire.

Zillow also announced it has dramatically expanded and improved its Zestimate algorithm, incorporating 20 times the number of statistical models than before that factor in more local and home-type variables and now integrate homeowner-edited home facts — such as the number of bedrooms, bathrooms or square footage. More than one million homes have been claimed and updated by their owners to date, contributing to improved Zestimate accuracy on many of these homes. According to the company, incorporating these changes along with continued algorithm upgrades have resulted in a 12% improvement in Zestimate accuracy(2) nationwide. Many larger metropolitan markets, such as the greater San Francisco, Miami, Los Angeles and Atlanta areas, have some of the most significant accuracy gains at 18%, 21%, 22% and 28% respectively.

“We’ve come a long way since Zillow’s launch nearly two years ago, adding more data on more homes along with numerous new products and features. The hard work of our team has been heavily supported by an incredible amount of participation from the Zillow community of homeowners, buyers, sellers and real estate agents,” said Lloyd Frink, Zillow co-founder and president. “Each day, more than 25,000 community contributions are made to Zillow.com — things like homeowner updates, photos, or Home Q&A. This type of active participation means a more accurate and transparent real estate community, which benefits everyone.”

Zillow Vice President of Data and Analytics Dr. Stan Humphries provided perspective on the magnitude of Zillow’s statistical processing effort, “To calculate Zestimates on nearly all homes in America, we process more than a decade of market data to generate over 13 billion historical Zestimates using 67 million statistical models. Our enhanced algorithm along with greater computing resources enable us to process this data at a more granular level than before, resulting in better accuracy.”

The company says that Zillow provides data, information and community features around all homes, not just those on the market today. In fact, 40% of all U.S. homes have been searched on Zillow(3) since the site launched in “beta” form in February 2006. With this latest release and round of improvements, Zillow now comes out of its “beta” phase.

More specific details about Zillow’s coverage and accuracy down to the county level can be found in its updated data coverage and accuracy pages that now show how often a Zestimate comes within 5%, 10% and 20% of the final sale price, which nationwide is 32%, 54% and 77% respectively. These pages will now be updated every three months, arming consumers and real estate professionals with the most frequent and detailed information possible, supporting the company’s commitment to information transparency.

The updated data and accuracy pages may be accessed through a link at the bottom of any Zillow.com page.

For more information, visit http://www.zillowblog.com.

Zillow.com, Zillow and Zestimate are registered trademarks of Zillow, Inc.

(1) According to the U.S. Census Bureau’s 2005 American Housing Survey, there are 91 million single family homes, condos and co-ops in the U.S.
(2) Zestimate accuracy is computed by comparing the final sales price to the Zestimate on or before the sale date.
(3) 37 million American homes have been looked up on Zillow, meaning someone visited the property’s individual Home Details Page.

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