can Zillow estimates be manipulated?

[cantab]

See http://www.zillow.com/homedetails/4960-Foothill-Blvd-San-Diego-CA-92109/16910245_zpid/

This house is listed at $1.1M with a Zillow estimate of $1.05M. Zillow’s own history show that the estimate has gone from 650K to 1050K in the last 24 months.

There seems to be no public data that supports the current Zillow estimate. Photos indicate that the house has been improved recently, but not enough to trigger an increase in the assessed value, which actually went down in 2012. The listing claims 1702 sqft, which may be true, but the public record still says 1472 sqft.

So my question is, what is the Zillow estimate based on?

Note: I am not a Zillow hater. I think most of their estimates are good. But is it possible to manipulate them?

[CA renter]

Way above 2008 price, so not sure how they arrived at that number…unless there was a major addition or something(?).

Of course, I’ve seen houses being flipped for crazy sums lately. I thought that appraisers were supposed to be more careful after the bubble fiasco, but they appear to routinely accept that a house can increase in value by $250K in three months via the magic of paint and flooring. 🙁

[DataAgent]

Eppraisal.com estimates the value to be a lot less:
http://www.eppraisal.com/home-values/property/4960-foothill-blvd-pacific-beach-ca-92109-182000518/

[moneymaker]

eppraisal is even further off than Zillow. Just for the fun of it I put in a house 2 doors down and eppraisal says it is worth less than half of what it sold for in December of 2013. I do believe Zillow can be wrong but I have no idea how to manipulate it. Zillow says my home has been falling as of late even though the last 2 houses sold on my block went for what I thought were ridiculously high values. Go figure!

[UCGal]

Public records don’t always reflect all permitted work.

When we added our granny flat – public records properly increased the bedroom and bath count, but did not increase our total square footage.

All of this was done on permit – so no clue why the public records are wrong.

I updated zillow to reflect the proper square footage and saw a big jump on the zestimate.

[DataAgent]

[quote=moneymaker]eppraisal is even further off than Zillow. [/quote]

Eppraisal estimates the value of my house about 10% higher than Zillow. Both estimates are high but Zillow appears to be a little more realistic over time.

I think all of these automated valuation services can be manipulated to some degree. For example, a neighbor listed their house for quite a bit ‘above market’ late last year. Zillow seemed to pick up their listing as a data input and our whole neighborhood got a bump in valuation.

[cantab]

I suspect this is the key point: “Zillow seemed to pick up their listing as a data input.”

It makes sense for Zillow to use listing prices as data. In this case the estimate is 95% of the list price, and 95% is in the ballpark as a typical sale-to-list ratio. But this creates an opportunity for manipulation. An unsuspecting buyer will see the Zillow estimate as support for the list price

[Aecetia]

I agree with this point about Z picking up listing for data input. Recently in my neck of the woods, there has been a similar bump in listing prices based on one home that came on the market in the 9’s and now there are others similarly priced. There have been no recent sales in this price range and based on the lack of offers, I think it is inflated. We shall see.

[Author]

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