This morning’s S&P Case-Shiller Home Price Index came in about where most housing “realists” thought it might and that group apparently includes one of its creators, Yale economist Robert Shiller, who had a few comments about the latest data.

The housing slump isn’t over.

Tax credits and historically low mortgage rates have failed to lift home prices so far this year. Prices fell 0.5 percent in March from February, according to the Standard & Poor’s/Case-Shiller 20-city index released Tuesday.

That marks six straight months of declines — a sign that the housing market is going in reverse.

“It looks a little like a double-dip already,” economist Robert Shiller said in an interview. “There is a very real possibility of some more decline.”

The co-creator of the Case-Shiller index, who predicted in 2005 that the housing bubble would burst, says he worries that home prices rose last year only because of the federal tax credits. That fear is shared by other economists. They note that weak job growth, tight credit and millions more foreclosures ahead will weigh on the home market.

Absent another extension of the homebuyer tax credit and/or some stunning job growth in the months ahead, it’s hard to imagine how home prices can go anywhere but down. The big question remains, “How much?”

In case you missed these comments yesterday by FHA Commissioner David Stearns, as reported in this story at the new Bloomberg/Businessweek, here they are again.

FHA lending last quarter may have topped the combined volume of government-supported Fannie Mae and Freddie Mac in a home-lending market that’s still a “government-financed market,” David Stevens, the agency’s head, said today at a conference in New York, citing research by consultant Potomac Partners.

“This is a market purely on life support, sustained by the federal government,” he said at the Mortgage Bankers Association conference. “Having FHA do this much volume is a sign of a very sick system.”

The FHA, which backs loans with down payments as low as 3.5 percent, insured $52.5 billion of home-purchase mortgages in the first quarter, compared with $46 billion of purchases of the debt by Fannie Mae and Freddie Mac, according to data compiled by Washington-based Potomac Partners.

The FHA and Fannie Mae and Freddie Mac, which regulators seized in 2008, have been financing more than 90 percent of U.S. home lending after a retreat by banks and the collapse of the market for mortgage bonds without government-backed guarantees.

In light of this sort of bold admission of the truth, it’s funny when you hear people who continue to say things like, “I think the real estate market has finally ‘turned the corner’. The bottom is now behind us and we shouldn’t see any more big price declines”.