For most mortals, economics is a dark and deeply confusing topic. The vocabulary is dense, the relationships contorted. Economists are notorious for offering two — contradictory — opinions on most topics. So forgive us if we are confused at the most recent forecasts of the global economic outlook.

In its most recent assessment, the Organization for Economic Cooperation and Development (OECD), a group that includes the world's developed nations, sees the bottom of the recession. It expects its 27 member-country economies to shrink 4.1 percent this year, which in fact is an improvement over its March forecast of a 4.3 percent decline. This is the first time in two years the OECD has made an upward revision.

Yet only days earlier, the World Bank downgraded its forecast for the global economic outlook. The international lender concluded that the world economy will shrink 2.9 percent this year; in March it had anticipated a 1.7 percent drop, which it then called the worst on record.

The easy explanation for the differing estimates is the sample. The OECD numbers account for about 80 percent of the world economy (the 27 members along with Brazil, China, India and Russia). We could blame the other, less developed economies for creating the drag on global growth. But developing countries are thought to be weathering the downturn better than the developed world — their financial systems have not been as badly hit — which would imply that an improving OECD forecast would mean better overall economic prospects.

Growth will vary. The OECD anticipates China will record 7.7 percent growth this year, an improvement of more than 1 percentage point. By contrast, the U.S. economy is expected to shrink by 2.8 percent in 2009 (an improvement over the 4 percent forecast earlier), Japan will contract 6.8 percent, and the economies of the 16 nations comprising the euro zone will decline 4.8 percent (worse than the 4.1 percent estimated earlier). By 2010, however, the entire OECD group is expected to average 0.7 percent growth — anemic, but an improvement over the last forecast of a 0.1 percent contraction.

The OECD credits the massive stimulus packages that have been implemented by most member counties for turning the tide. "A really disastrous outcome has become more of a remote risk," said the head of the OECD economics department, Mr. Jorgen Elmeskov. But, he conceded, the recovery is likely to be "weak and fragile."

Two problems are front and center now. The first is cleaning up bank balance sheets — an issue that Japan knows well. Failure to eliminate uncertainty about bank liabilities will mean that credit remains tight, and that will act as a brake on economic recovery.

The second problem is the prospect of massive government debt triggering inflation and halting recovery. While OECD experts encourage member governments to keep the fiscal pumps primed, they also urge them to begin developing "post-crisis policy strategies" to ensure that fiscal imbalances do not reverse hard-won gains when recovery is consolidated.

It is a fine line — and, again, one that Japan has walked with mixed success. In 1997, after years of stimulus packages finally sowed the seeds of recovery, the government increased taxes to get fiscal accounts back in order. That move killed the incipient blooms and plunged the economy back into stagnation.

The OECD warned member governments not to end the stimulus measures too soon. The Bank of Japan "should fight deflation through a strong commitment to implement effective quantitative measures until underlying inflation is firmly positive." According to BOJ policy board member Seiji Nakamura, the bank will continue with the special measures that it has used to stimulate the economy, such as buying commercial paper and corporate bonds. Those policies are set to expire in September.

For its part, the U.S. Federal Reserve is heeding the OECD's advice. Last Wednesday, the Federal Open Market Committee voted unanimously to maintain the rate for lending between banks in a record-low range of zero to 0.25 percent, and to keep the discount rate for commercial and investment banks at 0.5 percent. European governments have been more hesitant to open the spigots: That explains, in part, the sluggishness of the recovery in the euro zone.

Ultimately, however, the global economy will not recover to its previous heights. Credit was too readily available. Financial innovation — and what looks a lot like corruption — created bubbles. On the one hand, tighter financial regulation will curb the abuses and increase stability; on the other, it will result in significantly less capital being available. The OECD estimates that the level of trend output in its member countries is likely to be permanently reduced by nearly 3 percent. Lower output means higher unemployment. The lower the risk, the lower the rewards: That is an equation even noneconomists can understand.