Two Mid-Atlantic Cities Make Zillow's Top 5 Fastest Sellers (but...)

We came across the following article on Yahoo! Real Estate: U.S. Cities Where Homes Sell the Fastest

Among the Top 5, our very own Woodbridge, VA (Tied for #5) Alexandria, VA (#4).  So that's all well and good. But it's also a bit confusing.The article relies on Zillow's analysis of the median DOM for homes sold between mid-April and mid-July. It reports that Alexandria's Median DOM for this period was 74 days. However, when looking at the stats - from the MLS - on RBI, it shows an even faster median time to sell than that reported in the Zillow analysis!:

As you can see, the Median DOM is within a range of 26 to 33 Days for the months included in the article's analysis. You'd have to go all the way back to January of 2008 to see the median DOM at the 80-day level they report!  So what does this mean about the relative rankings of cities in this report?  And what does it mean about other numbers reported by national media outlets of this size? Not sure, but we checked on Alexandria's neighbors to see if, by chance, other local cities might have been incorrectly excluded from this exclusive list. Here's how Alexandria stacks up against Washington, DC and the greater DC metro:

Why didn't DC make the cut, how did its Median DOM actually stack up against San Francisco?  We don't have the San Fran data, so it's impossible to say. Why the huge discrepancy between numbers reported?  Tough to say without looking at Zillow's methodology and data sources. We thought maybe the Zillow methodology went against Days on Market Listing (DOML) rather than Days on Market Property (DOMP) - DOMP is what RBI reports on, but if that were the case then their numbers would likely be artificially lower. Maybe it's a rolling median, but that still wouldn't explain a doubling of the DOM figure. Any ideas?