The housing downturn that began in 2005, 2006, or 2007, depending on location, has tested the mettle of the economists whose job it is to figure out when and how the crisis will end.

Some economists argue, and with considerable justification, that government interference in the real estate market has made predicting the date of recovery from difficult to impossible.

That government interference manifested itself primarily in the Federal Reserve's purchase of mortgages from Fannie Mae and Freddie Mac, which affected interest rates until the program ended March 31.

The federal tax credits for home buyers, which boosted sales for more than a year, added to the confusion. The tax benefit kicked housing sales into gear; the end of the credit put the housing market back on life support.

"We misjudged the impact of the two tax credits," said economist Patrick Newport of IHS Global Insight Inc. "We expected the credits to both shift demand and increase sales and starts. It appears that the tax credits mostly shifted activity."

The level of interference is now much lower, and a clearer picture of the market is emerging, allowing economists, as well as civilians, the opportunity to predict with a bit more accuracy.

The "when" remains difficult to pin down, although the nonprofessionals - typical homeowners and renters - believe they have the answer.

Recovery will occur anywhere from 2012 to 2015 and even later, according to most of the 2,000 homeowners and renters surveyed by Harris Interactive in November.

The survey, commissioned by real estate search engine Trulia and foreclosure-tracker RealtyTrac Inc., found that just 4 percent thought the market had recovered already.

"Sellers and buyers are tamping down their expectations for a swift recovery in the housing market and bracing themselves for a long, slow climb back to a healthy real estate market," said Trulia chief executive officer Peter Flint.

"Government incentives have come and gone, and historic lows in interest rates have done little to spur recovery," he said.

From the responses, Flint says consumers have a "What's next?" attitude, "since they have lost faith in banks and their government to make good decisions."

What it will take for a market turnaround is a much easier question to have answered by the economists.

"On the face of it, getting the housing market to recover is quite easy, since it's well-established what drives housing," said economist Kevin Gillen, vice president of Econsult Inc., of Philadelphia.

That is, "You take a reasonable level of home building costs, combine household income growth with job growth, throw in a good dash of accessible mortgage credit, and - Presto! - you have a robust housing market," Gillen said.

All the government needs to do is reduce unemployment, grow the economy and keep inflation - and hence interest rates - in check, and housing will begin to recover.

"Of course, this should remind you of Steve Martin's old routine about his foolproof two-step plan to make a million dollars tax-free. 'Step One: Get your hands on a million dollars,' " Gillen said.

So, given that unemployment rose in recent weeks, credit remains tight for buyers as well as the typical home builder, and 30-year fixed-interest rates have risen in the last few weeks from a record low 4.17 percent to 4.61 Thursday, Martin's way is still the better bet.

Rates rose, says Freddie Mac chief economist Frank Nothaft, "after Europe made strides in its debt situation," allowing investors to leave the security of U.S. Treasury debt, causing bond yields and mortgage rates to rise.

"Key macroeconomic drivers of the economy - such as income growth, unemployment rate, and inflation - will affect the performance of the housing and mortgage markets in 2011," he said.

"Economic recovery should accelerate gradually over the year, with the second half of 2011 exhibiting more growth and job creation than the early part of the year," Nothaft said.

Employment is important because potential home buyers need a job, income, and savings to qualify for a mortgage, he said.

Improved consumer confidence is another, since if consumers are worried about their economic future, or whether house prices will fall, then they will be reluctant to buy.

Nothaft believes 30-year fixed rates will stay below 5 percent in 2011 and home prices will bottom in the first half and rise 1 percent for the year, combining to keep homeownership affordable.

With rising rates, and because most people able to refinance have done so already, mortgage originations will drop in 2011, although there will be an increase in loans to buy houses, he said.

Conventional wisdom says, since housing's bust led the United States into this downturn, then a true recovery cannot begin until housing recovers first.

"The problem with the housing sector is that, historically, it isn't so much an input to the economy, as an outcome of it," Nothaft said. "When the economy is generally doing well, so too is housing, but the reverse is not so clear."

Government intervention simply delayed further house-price declines, "while at the same time, blowing the taxpayers' money," Econsult's Kevin Gillen said.

"The government should tend to reducing the national debt, lowering and simplifying the tax burden, promoting job growth, and keeping the currency and macroeconomy sound," Gillen said.

"If it takes care of that, housing will eventually take care of itself."

Contact real estate writer Alan J. Heavens at 215-854-2472, aheavens@phillynews.com or Twitter: @alheavens