In recent months some really great, consumer friendly, easy to use real estate related web sites have been rolled out. They are using "mash ups’ to integrate data and maps. Zillow is an example of a really great web site. The site has the value of your home, called a "zestimate". I have checked the data on the site against data from a known and trusted source, the MLS, and have found that Zillows home value "zestimates" are not very close to the actual value of the home. In the Regional MLS there is a disclaimer that says that the data is deemed reliable but not guaranteed. There is no such disclaimer in Zillow, but they do call the home value a "zestimate", and state that it is to be used as a guide.
The data for the home prices in the twin cities used in Zillow Zestimates seems to be exactly the same as the data found in the county tax records. After using both web site to look up numbers I really do understand why people like Zillow, it is a nicer looking more user friendly site.
If a home has not changed hands for many years the county information about the property and the market value are way off. Zillow also uses comparable properties to adjust prices. Real estate agents and appraisers do the same thing but we have to use comparable homes that are near by. The comparable homes Zillow uses for my own home are in another city. Real estate professionals would not be able to use those homes as comparable.
Zillow acknowledged that the data about homes is not always accurate and now allows home owners to update the information with the right number of rooms square feet etc. Adjusting the property does not make it worth more money. In reality if a home is bigger or has more rooms it is worth more money, a smaller home with fewer rooms is worth less money. Home owners are supposed to pick new comparable homes after they make the adjustments, and then the price will be adjusted. Hard to do since the data for the comparable homes is also inaccurate.
Data in the Regional Multiple Listing Service is not always accurate either but they do have rigid standards and rules in place to keep the data as accurate as possible, and it is monitored by staff.
I have talked to some of the developers and owners of this new breed of web site. I am being told that not many people question or analyze the data. That is the problem. Companies put the data on the Internet and consumers assume it is accurate.
There is another web site that I will be mentioning next week called Neighboroo, it has neighborhood information, and is not yet a trusted source because they are not ready to say where the data comes from and the site is still beta. After talking to the developer I believe that this site will become a trusted source in the near future, and look forward to citing it in a post.
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Hi Teresa, it’s David from Zillow.com
This is a great review — you’ve taken time to understand our website and the nuances of its features. Thank You.
The more common reason for allowing owners to edit their home facts on Zillow is that the public record is often incomplete (missing the number of baths etc.) – but corrections were also an important motivator. It is not necessarily the case that houses that haven’t sold in ages have incorrect facts — but you are correct in that with time, they are more likely to have had unpermitted upgrades. Incomplete data is a bigger challenge than inaccurate data and we’re encouraged by the number of homeowners who have claimed their house and started to fill in the gaps.
We’re looking hard at having Zestimates be calculated using these owner corrections instead of the public record. This is a massive technical effort — collecting data from homeowners was just step one.
What’s definitely in the works is iterative improvement to the way comps are chosen — in both proximity and similarity to the house in question. Your case sounds like one we could learn from – I’d appreciate it if you could send me your address to the e-mail I used to register to comment – and promise that this information would not be shared beyond our internal analytics team.
We take data accuracy seriously – owners are required to claim their homes before they edit their facts and our staff reviews content that is flagged as malicious by users of the website.
Thanks again for your review.
David
I will send you the information about my house. Thanks for the comment.