The Real-Time National Housing Market Report is a new contender in the race to provide the most accurate housing data out there.

Using analyticals from 20 U.S. metros, the founders of Altos Research, plan to go head-to-head with the S&P's Case/Shiller Index, and the Office of Federal Housing Enterprise Oversight (OFHEO), each of which tracks same-home sales over time.

"When you're making investment decisions or trading derivatives, these lag times are simply killers," says Michael Simonsen, CEO and co-founder.

Where the Real-Time report differs from competitors is that it tracks listing prices, not closed sales prices, on over one million homes.

By that metric, prices in 18 of 20 markets tracked fell for the month of November.

• San Diego prices fell nearly six percent.

• Miami homes tooke the prize for longest days on market -- 137, with Minneapolis a close second at 125.

• Listings increased in Las Vegas by 6.6 percent over the past three months.

Gee, and I already had trouble sleeping at night.

Luckily, not all markets are doing so badly. New York, Denver and Dallas are holding their own, even while demand is weaker. Inventory fell more than 10 percent in New York, San Francisco and Washington, D.C. And, days on market grew substantially in Seattle, Tampa, Chicago and Cleveland, but homes for sale reduced by nearly 15 percent in Phoenix.

Tracking market conditions is a clever idea, but guess what, Altos? You weren't the first to think of it.

Realty Times has published daily market conditions for nearly 10 years. Click on Market Conditions, and go to any city of your choice on RealtyTimes.com

Like the NAR's Pending Sales Index, The Real-Time Report will be fun to read, but put it in perspective - it's forward-looking only, until the sales numbers come out.