Atlanta’s home prices were up an average of 6.3 percent during the past year, better than average gains across the country, according to a much-watched national survey released this morning.

However, the averaging of prices continues to mask a problem at the lower end of the market, especially in metro Atlanta, say some experts.

Atlanta’s price hike beat the 4.4 percent gain nationally, according to the S&P/Case-Shiller House Price Index, a calculation based on a three-month average.

Atlanta prices also rose more than the 5.2 percent average for the nation’s 20 largest metro areas. Among those 20, Atlanta was the ninth-strongest increase, said Case-Shiller.

“Home prices continue to appreciate across the country,” said David Blitzer, chairman of the index committee at S&P Dow Jones.

For the month, Atlanta prices were up 1.27 percent, according to Case-Shiller.

The economic fundamentals continue to support the real estate market, Blitzer said. “Overall, housing is doing quite well. In addition to strong prices, sales of existing homes reached the highest monthly level since 2007 as construction of new homes showed continuing gains.”

The overall national gain for the year was 5 percent, the same as last month.

The Case-Shiller composite for the nation’s 20 largest metros showed prices up 5.2 percent for the year, a deceleration from the 5.4 percent reported a month ago.

The national index has risen at a pace of 5 percent or more for seven consecutive months, Blitzer said.

Some experts say the use of averages blurs the differences between top and bottom. That is, values for the least-expensive homes are rising much more quickly than the values for the more expensive homes.

A key factor in that contrast is that inventory – that is, the number of homes for sale – is relatively greater at the low-end.

Fastest climbing prices for the past year were in Portland, Or., where prices climbed 12.5 percent, and Seattle, up 10 percent. Weakest gains were in metropolitan New York, up 2.0 percent.