Where will the housing market go in 2008? It's a question that's pondered as seriously in the halls of economic think tanks as it is around suburban kitchen tables.

Nearly everyone has something to say about the topic, but there's almost no consensus.

The National Association of Realtors predicts that sales of existing homes will rise in 2008. The Mortgage Bankers Association forecasts that housing will hit bottom in the fourth quarter. Moody's Economy.com sees housing prices continuing to decline through the beginning of 2009.

But what do they know? The N.A.R. told us that the housing market hit bottom at this time last year, and we now know what happened next. Sales of existing homes were down nearly 13 percent through November. The M.B.A. predicted last December that housing would stop falling sometime around midyear 2007. And in April, Treasury Secretary Hank Paulson concluded that the housing market was "largely contained" and the market's correction was behind us.

The good news about making predictions, economic or otherwise, is that you can always revise them when things don't turn out the way you expected. Perhaps Ed Lazear, a top White House economic adviser, put it best when he recently lowered his economic outlook based on a more protracted housing market: "There are some exceptions, but for the most part, our revisions are in line with other people's revisions as well, so I wouldn't point to any one specific factor. It's simply that the housing market decline has been more significant than we expected." Simple.

Of course, the capital markets were supposed to see into the housing crystal ball for us when the Chicago Mercantile Exchange started trading housing and futures and options nearly two years ago. But that hasn't quite panned out the way everyone predicted, either.

In May of 2006, the C.M.E. started a futures and options market based on the S&P/Case-Shiller Home Price Indices. It lets investors dabble in the housing market without actually buying real estate—either investing in hot real estate spots or hedging against their own homes in a down market.