Hacker News Board Hacker News, browsed like a classic message board
Live data from Hacker News

Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

washingtonpost.com

Post reply on HN
Print view View original

121–130 of 265 posts

Re: Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

#121

Post by azernik »

_m8fo wrote: post #52
mattkrause wrote: post #25

Earlier quoted context omitted.

If you want to try it, there are a few data sets kicking around, including a) https://www.kaggle.com/c/house-prices-advanced-regression-te... b) http://www.bis.org/statistics/pp_detailed.htm c) https://archive.ics.uci.edu/ml/datasets/housing If you had a really great model, you might be able to make some money with it--find underpriced (per the model) houses, buy them, and then try to sell them at the model's price.

That might be a good project actually. Try to predict previous houses prices from historical data. A retrospective analysis would be fun since you know what the "right answer" is and can adjust your model accordingly. It seems this and predicting the stock market have some similarities, but I think real estate is less volatile.

Make sure to separate your training and validation data sets! :-)

Re: Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

#122

Post by [deleted] »

strictnein wrote: post #19

The Zillow estimate used to be spot on in our neighborhood, for several years even. Recently they all plunged to 10-20% below market value, even though all sales data puts it at the previous mark. The weird thing is that they also went back and recalculated old "Zestimate" data as well. On April 2nd the estimate for our house was $617,453, which is more or less what it would sell for. It had been above $600k since Ju…

[deleted]

Re: Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

#123

Post by TeMPOraL »

strictnein wrote: post #19

The Zillow estimate used to be spot on in our neighborhood, for several years even. Recently they all plunged to 10-20% below market value, even though all sales data puts it at the previous mark. The weird thing is that they also went back and recalculated old "Zestimate" data as well. On April 2nd the estimate for our house was $617,453, which is more or less what it would sell for. It had been above $600k since Ju…

> The weird thing is that they also went back and recalculated old "Zestimate" data as well (...) there's no sign it ever got above $580k in the historic graph.

That sounds like a new level of shady.

Re: Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

#124

Post by sibmike »

Surely appraisals regulation is just another instance of mortgage regulations. But is it not the over regulated mortgage market that blasted in 2008? Was it because of zestimates? Nope? Well here ya go. Let the people speak their opinion and work on their ML.

Re: Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

#125

Post by bufordsharkley »

tehlike wrote: post #107
natoliniak wrote: post #4

Interesting. I wonder what would her argument be if Zillow simply reported the City/County tax assessors estimates which are usually even lower than Zillow's.

Tax assesment is useless in california?

Yes, because of Prop 13, assessments have very little connection to current market value.

Re: Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

#126

Post by cletus »

strictnein wrote: post #19

The Zillow estimate used to be spot on in our neighborhood, for several years even. Recently they all plunged to 10-20% below market value, even though all sales data puts it at the previous mark. The weird thing is that they also went back and recalculated old "Zestimate" data as well. On April 2nd the estimate for our house was $617,453, which is more or less what it would sell for. It had been above $600k since Ju…

I just went and tried this. The Zestimate for my place is... ludicrous. Probably 30% below market value. What's more, similarly sized apartments on the same floor vary by 15%!

I'd always thought this number was dumb but wow. This is even more ludicrous than I could've believed.

How can it be this far off with apartments with recent sales history in a building with lots of unit (and thus lots of sales activity)?

Could this be a case of them A/B testing on the Zestimate model to maximize lead generation with the "disagree?" link?

Re: Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

#127

Post by 2muchcoffeeman »

tehlike wrote: post #100
WaxProlix wrote: post #73

Earlier quoted context omitted.

This is the same in Seattle, where a house's asking price can be 550, its zestimate (or Redfin estimate) will be around 570, and the price it actually goes for invariably ends up around 700. This has been the case for months, and it can almost seem like some sort of conspiracy between realtors and these meta-agencies to game the market. There are plenty of comps that show prices are WAY above what the 'estimates' sho…

Yes. Some known realtors underprice the property to start bidding war. The foreign money in the hot markets also doesnt help. It sucks to see a house list for 2.9m and sell for 3.7. it happens quite often here in the bay.

In Australia a law was introduced where realtors had to provide realistic values for property that went to auction.

Before that if you were looking at 2 bedroom apartments, around Sydney, you'd just mentally add 400k. Not sure if it's better now or not.

Re: Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

#128

Post by mozumder »

beamatronic wrote: post #115
mozumder wrote: post #97

Earlier quoted context omitted.

How is the machine learning going to actually inspect the house?

With this [1] or this [2] [1] https://www.google.com/streetview/trekker/ [2] https://matterport.com/

How's that going to find rotting wood underneath the porch or a broken AC?

You know, what inspectors actually do...

Re: Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

#129

Post by tobyjsullivan »

_m8fo wrote: post #16

You would think real estate would prove to be one of the few real life fields where machine learning would be able to predict the prices pretty accurately. You have: 1. List price 2. "Favorites" on the MLS. 3. Square footage 4. Bedrooms 5. Bathrooms 6. Sold price for nearby properties 7. Sold price for nearby properties relative to their list price And the list goes on... Is it that difficult to predict? Literally th…

I tried once. The challenges came down to too many variables relative to sample size.

You gave just a small subset of variables which can impact price by over 20%.

The most important when I looked seemed to be:

- Neighbourhood (even street in some cases)

- Number of Bedrooms

- Year of construction

- Year of last renovation

- Floor (apartment)

- View (especially for apartments)

- Number of Bathrooms

- Year of sale

That last one, year of sale, is important because it actually impacts your training data. Do you use five years of data even though local real estate prices have been increasing at 10-20%/year? Or can that be normalized even though some neighbourhoods are changing at different rates than others?

I restricted my research to 1BR apartments in the city of Vancouver. There are some unique challenges for real estate in Canada, but basically the best sample size I could get was about 2000 sales (I think this was all the 1BR sales in a given year). Very few had information on all of the variables I listed above. Suffice it to say, you can't train a model of any quality on that data.

Re: Zillow faces lawsuit over ‘Zestimate’ tool that calculates a house’s worth

#130

Post by beamatronic »

mozumder wrote: post #128
beamatronic wrote: post #115

Earlier quoted context omitted.

With this [1] or this [2] [1] https://www.google.com/streetview/trekker/ [2] https://matterport.com/

How's that going to find rotting wood underneath the porch or a broken AC? You know, what inspectors actually do...

Now you are hitting a very interesting idea which would be to standardize home inspection reports in a machine readable format.
Post reply on HN