I mentioned in my last post that I'd try to keep up with Zillow's accuracy in my corner of the world. Below you'll find the results for Zillow's Zestimate vs. the Listing Agent's pricing for the 80302 zip in Boulder, Colorado for the month of March 2007.
If you are a math type, then you might want to take a look at this very simple spreadsheet
that I used for these calculations.
Results:
Zillow scored within 10% of the sales price only 64% of the time.
Realtors scored within 10% of the sales price only 73% of the time.
Overall it was a much worse performance for both groups. It's pretty obvious that I can't establish a trend yet, but if you take a look at the types of properties in this data set you'll see that they are quite a bit more expensive. You've got neighborhoods like Mapleton, Chautauqua, University, and Rose Hill. These are some prime locations in Boulder.
There are three properties that stand out as particularly troublesome for Zillow...but they also gave the agents some problems. They are:
1. 2156 Magnolia Drive, Boulder, CO 80302. List price: 789,000. Sold Price: 769,000. Zestimate: 680,546
2. 900 6th Street, Boulder, CO 80302. List price: 1,170,000. Sold Price: 1,055,000. Zestimate: 835,000
3. 556 University Ave., Boulder, CO 80302. List price: 3,850,000. Sold Price: 3,250,000. Zestimate: 2,004,283
For Magnolia Drive the Zestimate was off by 12%. The details page on Zillow did not account for 10 acres of land.
On 900 6th Street, the prices were of by 11% and 21% for the agents and Zestimates respectively. The MLS data sheet reported updated kitchen, bath, and wood floors which did not appear on the Zillow details page.
At 556 University, the agent was off by 18% and the Zestimate was off by 38%. This one seems to have given both parties fits. It was a unique property, and the Zillow details page made no mention of a 1bd/1ba carriage house. The lot can also be subdivided into two additional building sites of 7,000 and 7,500 square feet each.
I know, this was a snooze-fest of a post for anyone who is not hyper-analytical. I think I dozed off once or twice myself.
I think that keeping these statistics will, at the very least, help me to speak to my clients on a neighborhood by neighborhood basis in regards to Zestimates. Plus, if I keep writing posts like this it'll help all of you catch up on your sleep.
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