Fears of an economic slowdown are heightening anticipation of what Friday’s U.S. jobs report for January might reveal.

Stock markets have sunk after signs of weaker growth in the United States, Europe and China. Turmoil in developing countries has further spooked investors. The upheaval has renewed doubts about the Federal Reserve’s next steps.

Evidence of healthy U.S. job growth would help soothe those jitters. It would suggest that the world’s biggest economy is still expanding solidly enough to support global growth.

“The best antidote right now for all these problems is a robust U.S. economy,” said Carl Riccadonna, an economist at Deutsche Bank. “The whole world is watching, even more so than usual.”

Yet anyone looking to Friday’s report for a clear picture of the U.S. economy’s health might be disappointed. Unseasonably cold winter weather could distort January’s hiring figures. Revised estimates of job growth last year and the size of the U.S. population might further skew the data.

Another complication: A cutoff of extended unemployment benefits in December might have caused an artificial drop in January’s unemployment rate and perhaps a misleading snapshot of the job market’s health.

“Just when we need it most, the employment report may fall short,” Riccadonna said.

All the anxiety marks a reversal from a few weeks ago, when most analysts were feeling hopeful about the global economy. U.S. growth came in at a sturdy 3.7 percent annual pace in the second half of last year. The Dow Jones industrial average finished 2013 at a record high. Europe’s economy was slowly emerging from a long recession. Japan was finally perking up after two decades of stagnation.

Yet in just the past few weeks has come a barrage of dispiriting economic news. U.S. hiring slowed sharply in December. Employers added just 74,000 jobs, barely a third of the average gain in the previous four months.

On Monday, an industry survey found that manufacturing grew much more slowly in January than in December. A measure of new orders in the report plummeted to the lowest level in a year. That report contributed to a dizzying 326-point plunge in the Dow Jones industrial average.

Also Monday, automakers said sales slipped 3 percent in January. And last week, the government said orders to U.S. factories fell in December. So did signed contracts to buy homes, according to the National Association of Realtors.

A gauge of China’s manufacturing fell to a six-month low in January. And a report Wednesday said retail sales in the 18 European countries that use the euro fell in December by the most in 2½ years.

For all that, most economists remain relatively optimistic about U.S. growth. They attribute the recent weakness in the United States in part to unseasonably cold weather, which disrupted trucking and shipping. The weather might have lowered hiring in December by up to 50,000 jobs, according to several economists’ estimates. Few Americans want to test-drive cars or search for a new home in poor weather.

“I think the US economy is still doing just fine,” said Bob Baur, chief global economist at Principal Global Investors. “Maybe people are overreacting a bit.”

Baur still thinks U.S. growth will come in at nearly a 3 percent pace this year. That would be the best showing since 2005.

Growth at that level would also be enough for the Fed to continue winding down its monthly bond purchase program, Baur said. The Fed is buying $65 billion in bonds this month to try to keep interest rates low and encourage borrowing and spending. It has pared those purchases from $85 billion in December. Fed officials have said they will likely end the purchases by year’s end if the economy improves further.

Some positive signs have emerged. Fewer Americans sought unemployment benefits last week, the government said Thursday. Applications fell 20,000 to 331,000, suggesting that companies are laying off fewer workers.

A survey of service sector companies, including retailers, banks and restaurants, found that they grew faster in January than in December. The service companies, which represent about 90 percent of all private firms, also stepped up hiring, the survey found.

And payroll processor ADP said Wednesday that businesses added 175,000 jobs in January. That’s roughly in line with the average monthly gains of the past two years. It suggests that hiring could have rebounded a bit from December’s disappointing result. Still, ADP’s figure was also lower than the 227,000 jobs it said were added in December.

Yet ADP’s figures cover only businesses and frequently diverge from the government’s more comprehensive count.

Another unknown is the effect of the expiration of emergency unemployment benefits on Dec. 28. Benefits for about 1.4 million unemployed were cut off. Many of those people might have given up on their job searches in January. They had been required to look for work to receive benefits.

People out of work aren’t counted as unemployed unless they’re actively seeking work. If many people stopped looking for a job last month after their benefits ran out, the number of unemployed would fall. And so would the unemployment rate.

There’s no way to know how all these different trends will affect Friday’s report.

“We view this month’s (jobs) results as pretty much of a crapshoot,” said Joshua Shapiro, an economist at MFR Inc., a forecasting firm.

(AP)