If you’ve ever gone online to check out the value of your home or to make comparisons, you aren’t alone. Online home value estimators can be a handy tool in some cases, but you have to understand their limitations.

Zillow’s Zestimate is perhaps the most well-known estimator, but Redfin has one too.

Below, we talk about what you should know about home valuation tools, also known as automated valuation models or AVM.

What is an Automated Valuation Model?

AVMs are computer-driven algorithms and formulas that use basic property features paired with pricing trends and local market information to create a value range or an estimated value for a home.

There are some cases where a lender might use an AVM to quickly get a potential estimate of the value of a property.

All the AVMs use their own formulas and may pull data from different databases. As you might imagine, the estimates’ reliability and accuracy depend primarily on the quality and integrity of the data they’re pulling information from.

There are a lot of underlying assumptions made with an automated model.

For example, AVMs work on the assumption that all properties are in a similar condition to one another. There’s no way for these automated algorithms to consider if a home is in poor condition or if upgrades have been made.

Due to the fluctuations in the figures AVMs come to, lenders will set policies on whether they’ll use them and, if so, which they’ll use.

How Do Zillow Zestimates Work?

Zillow’s well-known Zestimates are based on what the company says is a proprietary algorithm. Zillow reports the estimates include data from public records and data users submit.

The company doesn’t claim that they’re 100% accurate. If all the properties within a small radius are similar, the prices are more accurate because there are less likely to be major variances throwing off the algorithm.

If the estimates come from a neighborhood with older homes, they’re likely to be less accurate. Some homes will have been improved and maintained over the years, and others won’t have been.

The accuracy of a valuation is measured using an error rate. An error rate calculates how often the algorithm is wrong. More specifically, how often the value of a property as measured by the AVM is very different from the sales price of a home.

The Zestimate gets within 5% of a home’s actual sales price more than 82% of the time. It’s within 10% of sales price more than 95% of the time and within 20% nearly 99% of the time.

That can sound pretty accurate at first, but it’s less impressive when you figure out how many tens of thousands of dollars these variances can represent.

The Zestimate median error rate goes up to nearly 7% for off-market homes. If a home hasn’t been sold lately, there’s not much data that an AVM can pull on it.

Over time, the algorithms tend to get more accurate. Zillow says that it will make offers to buy homes at their Zestimate price in some markets, or at least it did when Zillow Offers was operational, which it recently announced was closing down.

Realtor.com Offers Three Figures

Realtor.com takes a different approach when it offers online users home value estimates. The company pulls estimates from data provided by different companies it partners with. There are three estimates so that people can see the picture of how much their home is worth is more variable than what they might get from just one figure.

Redfin vs. Zillow

Redfin and Zillow are two competing tools for estimating the value of a home. They can sometimes give different figures for the same property.

Overall, Zillow’s Zestimate seems to be more accurate. The median error rate is a little lower than what’s calculated for Redfin, including both on-market and off-market properties.

Redfin is very transparent, though, which is an advantage it has. Redfin provides a lot of information on how they get their figures.

You have to remember that while these tools might give you a general idea of how much a home is worth, they’re not the same as an appraiser.

Before a lender signs off on a home loan, they require an appraisal. Appraisers do a walk-through and then write a report. They will also include market data and comparable properties, so this will be much more accurate than what you see online.

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480-213-5251

A new home appraisal rule just went into effect—the first time in 25 years that “federal regulators have increased the property value limit of the homes that require an appraisal as part of the selling process,” said REALTOR® Magazine. The rule exempts some home sales priced at $400,000 and below from requiring an appraisal. That figure was previously capped at $250,000. “The new rules likely apply to about 40% of home sales, regulators estimate.”

So how will this affect home buyers and sellers? First, it should be noted that those homes that do receive the exemption still have to be evaluated “to provide an estimate of the market value of real estate collateral,” said Housingwire. “The agencies state that the evaluation must be ‘consistent with safe and sound banking practices.’ To that point, the rule establishes that an evaluation “should contain sufficient information and analysis to support the regulated institution’s decision to engage in the transaction.”

Also, the new exemption is not applicable for homes using FHA, HUD, VA, Fannie Mae, or Freddie Mac financing, which eliminates a huge percentage of homes right off the top.

If you are in a position to buy or sell a home that no longer needs an appraisal, should you still proceed with one? Here’s why you may want to consider it.

What is an appraisal?
“A home appraisal is an unbiased determination of the fair market value of the home by a professionally-trained third party,” said Forbes. “While that may sound complicated, all it means is that it’s a chance for someone who’s not personally involved in the sale of the home to give a true representation of the home’s worth. It’s worth noting that an appraisal is entirely separate from a home inspection. The former deals with the financial value of your new home. The latter is an inspection of the functional quality of your home’s systems, like HVAC and plumbing.”

There are a number of factors that contribute to that fair market value. “In a purchase-and-sale transaction, an appraisal is used to determine whether the home’s contract price is appropriate given the home’s condition, location, and features,” said Investopedia. While the evaluation process is intended to provide guidance when it comes to pricing, it is unknown at this point how those evaluations will compare to appraisals, if they will carry the same weight in terms of establishing home value, if they will disproportionately favor the lender, etc.

Value protection
Buyers and sellers each have a vested interest (literally) in knowing how much the home they are buying or selling is worth. For sellers, an appraisal can help inform the listing price, and may also be able to help a seller justify a higher listing price because of improvements they have made to the home.

On the other hand, if a home appraises for less than the sales price, buyers have a negotiating tool. “An appraisal is important because it protects your investment,” said Forbes. “It’s there to ensure that, as the buyer, you don’t pay more than the home is actually worth. It’s also important for securing financing. In today’s mortgage industry a bank will only give you a loan up to the fair market value of the home. Therefore, if an appraisal comes back lower than the purchase price, the lender may only issue you a loan for the appraised amount.”

Position Realty
Office: 480-213-5251

I got an email from Zillow last week. Seems my house has gone up in value another $2,000+ dollars in the past 30 days. And it’s going to rise another 3.5% in the next year, according to their Zestimate®. Fab!

Except that it’s just speculation. When it comes to Zillow’s Zestimates, you have to take the numbers with a grain of salt. Make that a big shake of salt, right over your shoulder. And maybe a stiff drink. And a frank conversation with your real estate agent, give us a call.

“Shoppers, sellers and buyers routinely quote Zestimates to realty agents – and to one another – as gauges of market value,” said the Los Angeles Times. “If a house for sale has a Zestimate of $350,000, a buyer might challenge the sellers’ list price of $425,000. Or a seller might demand to know from potential listing brokers why they say a property should sell for just $595,000 when Zillow has it at $685,000. Disparities like these are daily occurrences and, in the words of one realty agent who posted on the industry blog ActiveRain, they are ‘the bane of my existence.'”

Are faulty Zillow estimates irritating, dangerous, somewhere in the middle? It all depends on your personal situation. A real estate investor, a seller in a high-end neighborhood, or an obsessive real estate watcher (ahem) may be able to brush off a $15,000 error. But for many people across the country, the word of Zillow might as well be the word of God. So, yeah, dangerous.

Price errors

Errors in sales prices are one of the issues Investopedia pointed out in its look at Zillow’s Zestimates.

“Zillow factors the date and price of the last sale into its estimate, and in some areas, these data make up a big part of the figure. If this information is inaccurate, it can throw off the Zestimate,” they said. “And since comparable sales also affect a home’s Zestimate, a mistake in one home’s sales price record can affect the Zestimates of other homes in the area. The Zestimate also takes into account actual property taxes paid, exceptions to tax assessments and other publicly available property tax data. Tax assessor’s property values can be inaccurate, though. The tax assessor’s database might have a mistake related to a property’s basic information, causing the assessed value to be too high or too low.”

In June, Zillow’s much-maligned (by industry experts, anyway) Zestimates got an upgrade with a new algorithm. Zillow CEO Spencer Rascoff has famously called his company’s price estimates, “a good starting point” and copped to a median error rate of approximately 8%. With their new algorithm, they say it’s dropped to 6.1%.

John Wake, an economist and real estate agent from Real Estate Decoded, applied Zillow’s updated 6.1% margin of error to “Zillow’s own estimate of the median sale price in the U.S. in May 2016 of $229,737 and got a typical error of $14,000. He then took a sample city, Denver – a city in which estimates are actually more accurate than average” – and found “the error spread in 2016 is a lot tighter and more focused on the bullseye of the actual sales price,” but that “their Zestimates are scattershot.”

In his example, “a Denver home has a fair market value of $300,000. According to Zillow’s Zestimate Accuracy Table, 10% of their Zestimate prices were off by more than 20% from the actual sale prices. Half of that 10% are Zestimates that are too high by 20% or more, and half are Zestimates that are too low by 20% or more. That means you have a 5% chance Zillow will give you a Zestimate of $360,000 OR MORE, and a 5% chance Zillow will give you a Zestimate of $240,00 OR LESS. Yikes!”

Missing data

It gets even more complicated without all the data that gets fed into Zillow’s algorithm. Limit the available info and the margin for error grows.

That same email I received included a couple of new listings and info on recent sold homes in the area. Notice anything interesting about these recent sales?

Yep, no sales prices. Texas is one of about a dozen states without a mandatory price disclosure law, which makes property appraisals challenging and which makes it even more difficult for Zillow to come up with an accurate Zestimate since it eliminates one of their key data points.

In the case of my home, they’re a good $11,000–15,000 high on their sales price estimate. And that’s based on my direct knowledge of sales prices in my neighborhood—not list prices, not tax assessments, and not assumed sales prices based on trends.

Which brings up another issue that leads to inaccurate estimates. In many neighborhoods, sales trends and prices vary street to street. But Zillow’s estimates are a one-size-fits-all program. In my masterplan, the building of high-density units on the southern edge of the community a few years back took a bite out of the value of homes on the perimeter streets. Sales of homes with a first-floor master also get a bump here.

And then there’s the fact that this community is also split between two elementary schools. Zillow wouldn’t know which one buyers prefer and wouldn’t account for a difference in sales price between two otherwise comparable homes. But, people who live here would, and so would the local real estate agents.

Which only reinforces the importance of working with one. Give us a call if you want a more accurate value for your home. 480-213-5251