The Dallas housing market lost more ground in the latest gauge of U.S. home prices.

Home prices in March fell 3.3 percent from a year earlier in Dallas, according to the latest measure from Standard & Poor's Case-Shiller index.

The report compares home price changes in 20 major U.S. cities. Nationwide, home prices dropped more than 14 percent in March compared with March 2007 – the biggest such slide in 20 years.

"The steep downturn in residential real estate continues," Standard & Poor's David M. Blitzer said in the report. "There are very few silver linings that one can see in the data."

All but one of the markets – Charlotte, N.C. – in the survey had declines.

And six of the cities had falls of more than 20 percent.

The negative home price report for Dallas comes just a week after another survey by the Office of Federal Housing Enterprise Oversight said prices in the area were up more than 3 percent for the first quarter.

However, the two studies measure home values differently.

Case-Shiller tracks the prices of typical single-family homes in each metropolitan area. The survey does not include condominiums and townhouses. It covers only existing properties – no new construction.

The Case-Shiller researchers say they compare "arm's-length sales" of specific single-family homes over time. The conflicts in home price data make it hard to judge what's happening in the market.

"It's not just the laymen that are confused," said Dr. James Gaines, an economist with Texas A&M University's Real Estate Center.

"It really doesn't help any of us when the primary sources of data contradict each other.

"I'm doing a speech in Dallas in another week or so, and I'm not sure what I'm going to say, whether home prices are up or down or what," Dr. Gaines said. "I do know I'll be saying that the market is very spotty, for sure."

Market conditions can vary greatly depending on the price range and neighborhood, he said.

Another first-quarter study of Dallas-area home sales prices by the National Association of Realtors showed a 2.1 percent drop in home prices here.

In the Case-Shiller report for March, Las Vegas had the biggest decline in the country – 25.9 percent – followed by Miami, which had a 24.6 percent dip in prices.

Dallas is the only Texas city in the survey.