How does Zillow’s accuracy rate work? Let’s talk about two important points. I’m not writing because I’m angry, but only because the public places enormous trust in this brand, and I see this accuracy rate quoted everywhere. Well, let’s at least know the fine print so we can have informed conversations.
Two quick points on Zillow’s accuracy rate:
1) Median makes all the difference: Zillow says their median error rate is 5% for the United States. That sounds impressive, but we have to realize this is a MEDIAN error rate, which means the Zestimate is within 5% of the purchase price only half the time. So Zillow’s slogan could be, “We’re within 5% half the time.” But that doesn’t sound as polished as “Our median error rate is 5%”.
2) Zillow uses the most recent Zestimate: This is such an important point – even if it feels a little technical. I have an example to help show what I mean too. Zillow states “Zestimate accuracy is computed by comparing the final sale price to the Zestimate on or before the sale date.” Let me show you why this matters.
An example: Imagine a property listed for $380,000 and the Zestimate was also $380,000. But then after a series of price reductions, the home sold for $350,000. That would be 8 percent lower than the original Zestimate. That’s not very good, right? Well, now imagine as the list price was reduced, so was the Zestimate, and the most recent Zestimate was $353,000, which is only 1 percent higher than what the property sold for. Here’s the kicker: The home may have sold for 8 percent below the original Zestimate, but for its accuracy rate Zillow can claim 1 percent because it uses the most recent Zestimate instead of the original one.
In short, the most accurate stat here would be 8%. After all, the home literally sold 8% lower than what Zillow said it was worth. Thus when Zillow uses the most recent Zestimate instead, it’s a clever way to get much sexier stats.
One more thing.
Chasing the List Price & Fixer Upper TV show: What sort of effect does the list price have on the Zestimate? In other words, does the list price actually change Zillow’s value? This might not happen in all cases, but here’s a glaring example of the “shotgun” house from the TV show Fixer Upper. It’s a one-bedroom that was listed for $950,000 and didn’t end up selling.
In this example the list price was outrageously high, but Zillow’s algorithm looks to have simply matched the Zestimate to the list price. This might not happen in all cases, but it certainly did here.
I hope that was interesting or helpful.
Article I wrote: Here’s a piece I wrote about online valuation sites for Comstock’s Magazine last month.
CLASS I’M TEACHING: I’m doing my favorite class at SAR on May 28th from 9am-12pm called “How to Think Like an Appraiser.” Sign up here.
Questions: What do you think? Anything else to add?
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