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Zillow Brings Zestimates to Leavenworth

Posted by Geordie Romer on June 20, 2011

Last week Zillow, the online real estate portal, announced that they had done some big changes to their database.
 We added Zestimates to more than 25 million new homes, bringing the number of homes on Zillow with data, Zestimates and Rent Zestimates to approximately 100 million. That’s more than three-quarters of all homes in the country. We improved the algorithm models that better incorporate user-submitted data and market data. This has improved the Zestimate median margin of error to 8.5 percent nationwide. Previously, it was 12.7 percent.
As was expected, home value estimates (called “zestimates”) changed in some parts of the country and they weren’t always accurate.
Zillow explains how they derive these Zestimates:
We compute this figure by taking zillions of data points – much of this data is public – and entering them into a formula. This formula is built using what our statisticians call “a proprietary algorithm” – big words for “secret formula.”  Currently, we have data, Zestimates and Rent Zestimates on approximately 100 million homes on Zillow.
For years, I’ve just been a spectator when it comes to the much debated Zestimates because Chelan County and Leavenworth haven’t been given zestimates in the past. The online data needed from the Chelan County Assessors office and/ or sold data from local Multiple Listing Services wasn’t available to help Zillow with their zestimates.
Until now..
How did Zillow do? I’d probably give them an F. I could give them a D or D- for trying but I think almost any observer could tell that the data isn’t very good.
My first example is a listing I have for sale. It’s a condo at Alpine Place  off Icicle Road.
Zillow has always had a problem with duplicate listings, but it’s funny when THE SAME HOUSE gets two different zestimates. (It must be the quarter bath?)

Next up, I decided to spot check some listings. What better place than to look at houses that recently sold.
This is public data and these are houses that have closed, recorded with the county and many of them were financed by a bank and appraised. I used the last 10 home sales in Leavenworth that Zillow has data for.
Sold Price $700,000 Zestimate $246,400
Sold Price $213,000 Zestimate $157,600
Sold Price $205,00 Zestimate $56,000
Sold Price $230,000  Zestimate $162,700
Sold Price $609,500 Zestimate $260,200
Sold Price $165,000 Zestimate $185,700 
Sold Price $330,000 Zestimate $209,000
Sold Price $280,000 Zestimate 170,000
Sold Price $225,000 Zestimate $127,100
Sold Price $207,000 Zestimate $85,000
So what do you think? Is Zillow a credible source for info on the value of your home?
Would you use Zillow to help price your home for sale or to help you decide how much to offer on a house for sale?
Required Disclaimer
NOTE: This representation is based in whole or in part on data supplied by the North Central Washington Association of Realtors or its Multiple Listing Service. Neither the Association nor its MLS guarantees or are in any way responsible for its accuracy. Data maintained by the Association or its MLS may not reflect all real estate activity in the Market.



    If you’re planning to buy a home in this area, the best place to start is with the Leavenworth Home Buyer’s Guide.

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