Most of Wall Street is probably happy to leave March behind, but April may not prove to be any easier, with market-moving economic data bookending the week.

Probably not the best way to start the month would be with a crummy

National Association of Purchasing Management

Purchasing Managers' Index

for March, but after Friday's gloomy

Chicago Purchasing Managers' Index, that's what we're most likely facing.

The Chicago PMI, which measures manufacturing sentiment in the Midwest, tumbled to 35, its

worst level since 1982. The figure is typically a good indication of how the PMI, or NAPM report, is going to look. For example, February's Chicago PMI hit 43.2, up from 40.2 in January, while February's NAPM report also rose slightly from January, coming in just above the consensus forecast. It stood at 41.9, up from 41.2 in January. Economists expected a reading of 41.5.

Still, Paul Christopher, senior economist at

A.G. Edwards

, said that between the Chicago PMI and the NAPM report, there's normally a correlation of about 50%, so, in effect, the Chicago number doesn't necessarily point to the national number that follows.

Before the Chicago PMI was released, March's NAPM report was forecast to come in at 42.2. A reading below 50 signals economic contraction, a number above 50 expansion. The March NAPM is scheduled to be announced Monday; it's always released on the first business day of the month.

Even if the NAPM number falls as much as Chicago's, Christopher said "it doesn't mean the economy is falling off the cliff."

Instead, he said that what we could see is that the manufacturing industry has cut back on production so much that it could eat up extra inventory, which is an encouraging sign, especially as consumer confidence is still fairly strong.

Christopher said a drop in production means manufacturers have responded to the inventory excess.

If, however, "consumer confidence has just taken a breather before it goes down further and we see manufacturing fall even more, it would indicate that not only do we have a ways to go, but the economy would be in trouble and on the brink of recession," Christopher said. "That would be a bad thing."

Federal Reserve Chairman

Alan Greenspan and his cohort will be watching the number for sure.

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Christopher said, "We saw them move in early January after the PMI came out, but I think they believe the economy is not as weak as the Chicago number might suggest."

The other major piece of economic news that the Fed will be watching is the monthly

employment report, to be released on Friday. It's forecast to increase by 56,000 nonfarm jobs. Last month, the market was thrown off by the stronger-than-expected jobs report, which reported an increase of 135,000 -- almost double the 68,000 economists had forecast.

Christopher said the number needs to come in positive and the unemployment rate not to have risen a lot to keep market tumult at bay.

Finally, the next most important data are car and truck sales, to be released at the beginning of the week.

"If we were to retreat from February levels, that wouldn't be a good thing. December's numbers were very weak and they bounced back in January and February, so if we were to retreat again, that would signal a relapse," Christopher said.

Now, if the data that come out next week are mixed, Christopher said, "that's what you'd expect from an economy that is transitioning" and the Fed probably will stay with its theory that the economy is doing better now.

He said there's a lot going for the Fed's theory, including such signs of optimism as consumer confidence being well above levels it reaches in a recession, an unemployment rate that is very low, and incomes that are growing at about 4% ahead of the rate of inflation. Also remember that interest rates are low and the dollar is strong.

"How can you have a recession if all those things are doing well? We're in a severe inventory correction that's beginning to work itself out and the consumer is going to do his and her part," Christopher said.

But Wait -- That's Not All

In addition to some potentially nasty economic numbers, the market will have the pressure brought on by an expected slew of earnings warnings and its first big earnings announcement of the first quarter.

Phil Orlando, chief investment officer at Value Line, said if it's not already obvious, we are looking at a record number of negative preannouncements, which he doesn't see slowing down anytime soon.

While Orlando says he wouldn't be surprised by any negative preannouncements, he does see such economic-sensitive sectors as semiconductors, computer hardware makers and fiber optics being hit disproportionately harder than other sectors. He said areas that appear to hold up better are storage and software companies.

As is tradition, blue-chip

Alcoa

(AA) - Get Alcoa Corp. Report

will be the first bellwether to report first-quarter earnings. The

Thomson Financial/First Call

14-analyst estimate is 44 cents a share, which is down from year-ago earnings of 48 cents a share.