Comments on: Redfin and Zillow: Stats of a Feather

By: Homes in Eugene Oregon

Homes in Eugene Oregon — Thu, 03 Jan 2008 22:43:03 +0000

I’ve actually sold one of my clients homes through Zillow. He was researching his homes value and it just so happened to be that my listing was a couple blocks away from his home. He called me up and we had a transaction in play within a week. Thanks Zillow.

By: Zillow Needs More Money and Gets It

Zillow Needs More Money and Gets It — Sat, 22 Sep 2007 07:59:25 +0000

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By: Danilo Bogdanovic

Danilo Bogdanovic — Tue, 06 Mar 2007 16:14:27 +0000

Great post and I’m right there with you. I did a post a while back on the accuracy of Zillow and other AVMs followed up by an update post just a short while ago.

David from Zillow left a few comments on my posts saying that my conclusions were incorrect and that the median margin of error was 7.8% rather than what I had concluded. But the data I had (which was supplied by Zillow itself) clearly showed otherwise.

Seems that they’re pulling these numbers out of thin air and that they think the public is too dumb to see otherwise after reviewing the true data.

By: sellsius°

sellsius° — Sun, 04 Mar 2007 02:41:58 +0000

Good question Michael. It depends on what you want to know.

By: Michael Daly

Michael Daly — Sun, 04 Mar 2007 02:27:27 +0000

So – where do we get reliable information and statistics?

By: sellsius°

sellsius° — Sun, 04 Mar 2007 00:56:42 +0000

The statisticians’ bag of tricks never fails to amuse us.
Company averages do not indicate the ability of a particular agent to save you money on a particular home. We have used the example of zillow. Just because the median error rate is 7.5% is no reason to rely on a zestimate on a particular home. The forest is not the tree.

By: Kevin Boer

Kevin Boer — Sat, 03 Mar 2007 23:21:58 +0000

As somebody who takes great delight in crunching numbers, let me say that for the entertainment value, it’s a lot of fun. Tell me what outcome you want, and I can probably find you a data set and a methodology that will prove my point.

Republicans tout the stats that show the tax cuts over the recent years have gone disproportionately to the middle class; Democrats tout the stats that show these same tax cuts have overwhelmingly benefited the rich.

They’re both right.

By: Realivent Real Estate Technology Blog » Blog Archive » All the real estate flunkies are silent

Sat, 03 Mar 2007 11:05:44 +0000

[...] Sellsius Redfin and Zillow: Stats of a Feather [...]

By: sellsius°

sellsius° — Fri, 02 Mar 2007 18:31:39 +0000

Thanks Mark. It’s always great to hear from an expert on these matters.

By: Mark Brandemuehl

Mark Brandemuehl — Fri, 02 Mar 2007 17:26:37 +0000

Since I’m a stats junky who hates it when the media jumps all over the latest study that shows cancer risk going up by 10% (from a 0.01% chance of getting that particular cancer to a 0.011% chance…), I have to comment.

It seems to me that independent of what you’re measuring. a 1 percentage point difference between two means, especially when one distribution is a small number of samples (Redfin’s sales) and one is large (overall market) means nothing unless you have done a statistical test for significance to determine the probability that the two distributions are really different. I’ll bet the significance of the difference is pretty low – in other words a serious statistician would dismiss this difference as meaningless.

In my opinion, reasonable (though somewhat dishonest) marketing, complete junk stats.

Cheers,

Mark B.
VP Marketing at Movoto.com