Mortgage Rates 30 yr fixed 3.80% 15 yr fixed 3.20% 5/1 ARM 3.84% 30 yr refi 3.82% 15 yr refi 3.20% Find personalized rates:   Rates provided by Bankrate.com.

QUICK VOTE    Are the drops in home sales and home building worrisome signs for the housing market?   Yes   No   Unclear    View results

NEW YORK (CNN/Money) - No one's really sure if the nation's housing market is a bubble at risk of bursting, or fairly priced with more upside ahead.

But analysts generally agree that low mortgage rates and other factors have boosted the market over the last five years, through a recession, job losses and the Sept. 11 attacks.

Still, some cracks are starting to show.

Reports on housing starts and new home sales, both considered leading indicators of the housing market, posted much sharper-than-expected declines in November, although December starts rebounded smartly. And the November report, the most recent available, showed median new home prices showing a slim but rare year-over-year decline.

So are home prices set for a tumble? Here are three major areas to watch for warning signs of trouble ahead.

A key factor supporting the real estate prices are continued low mortgage rates. Even economists who have warned of a housing bubble for several years say low interest rates have helped the housing market stave off problems.

The Freddie Mac survey of 30-year mortgage rates was at 5.74 percent in the most recent survey, which, while up from the 5.23 percent low seen in June 2003, is still comfortably below the 6 percent level considered to be low by most economists.

"The biggest surprise to me has been that interest rates have stayed as low as they have as long as they have," said Dean Baker, co-director of the Center for Economic Policy Research.

Baker said his projections are that rates will rise by about 1 percentage point this year, which he warned would be enough to raise borrowing costs and start driving home prices lower on a national basis, as buyers can no longer use the cheap financing to buy more expensive homes.

But other economists who aren't as worried about a bubble argue it'd take a sharper increase in rates, up to 7.25 or even 7.5 percent, before it starts to cut into home sales. And they say even rates that high would cut the pace of price increases for homes, rather than send housing values lower.

Doug Duncan, chief economist for the Mortgage Bankers Association says that even in 1983, when interest rates rose by 2 percentage points and the number of home sales plunged, median housing prices increased, albeit by less than the rate of inflation.

"We've had only two or three quarters since World War II when national average house price fell, and it's never happened for a full year," said Duncan. "That's not to say that it can't happen. But we've been through some quite wide swings economically during that time."

Duncan says that the reason he has the most faith in today's home prices is that demographics and sales results suggest continued strong demand for housing.

"The leading edge of the Baby Boomers is now 59 years old and that's only the leading edge. Our figures show that we don't see peak home ownership until age groups reach their 60s," he said. "They're not done buying housing."

Duncan points out that the supply of homes on the market is still near historically low levels -- a bit over four months, down from nearly five months only a year ago.

But Wachovia Securities Chief Economist John Silvia says that some of the demand for second homes could be most at risk if housing prices do start to show weakness, with resort areas near the coasts being most at risk if there is a reversal in the housing market.

"You have the Baby Boomers having the resources to buy condominiums, betting on the increase in value in the next six months," said Silvia. "That activity may be the first to feel the crunch if the housing bubble bursts."

Silvia said the greatest risk is that despite various challenges for the economy as a whole, the housing market has never really been tested.

"The market has not seen a negative sharp change in fundamentals," said Silvia. "You haven't seen a sharp rise in interest rates or a signal that the money isn't there to keep lifting prices."

Silvia said one of the most serious threats to the housing market could be a sharp drop in the dollar's value, rather than the slow steady decline seen for the last couple of years.

That fall could dry up foreign investment in U.S. markets, including the secondary mortgage markets, and cause a sharp rise in interest rates coupled with a sharp increase in inflation.

But Silvia says that short of that kind of shock, he doesn't believe the housing market is a bubble ready to burst, at least on a national scale.

"Home buyers need something visible on-screen to surprise them," said Silvia. "If it's the dollar gradually losing another 10 percent or mortgage rates creeping up 1 percentage point, that's not going to do it."

Baker disagrees, saying that the strength of the housing market in recent years has left it in uncharted territory, similar to the stock market valuations in early 2000 just before that market bubble burst.

"Normally when you talk about housing bubbles bursting, you're talking about a specific local market," said Baker. "But we've never had a nationwide run-up in home prices like this. I don't think it's realistic to think the decline won't also be national. I think a 15 percent nationwide decline is very plausible. In many bubble areas, could be looking at 20-25, maybe 30 percent declines."