By NICK WINGFIELD

Apple has made its first attempt to quantify how many American jobs can be credited to the sale of its iPads and other products, a group that includes the Apple engineers who design the devices and the drivers who deliver them — even the people who build the trucks that get them there.

On Friday, the company published the results of a study it commissioned saying that it had “created or supported” 514,000 U.S. jobs. The study is an effort to show that Apple’s benefit to the U.S. job market goes far beyond the 47,000 people it directly employs here. Apple, based in Cupertino, Calif., released the study on its website but declined to say why it published the results. The company’s employment practices have come under closer examination. Apple and other high-tech companies, including Internet companies, create relatively few jobs compared with other stalwarts of U.S. business, like General Motors and General Electric in their heyday. Apple, which has recently become the most valuable company in the world and holds nearly $100 billion in cash, has created more jobs overseas, approximately 700,000 through a network of suppliers that make iPhones, iPads and other products.

A number of companies, including Microsoft, have commissioned similar research aiming to tally up such indirect employment, by suppliers and other partners. The use of “job multipliers” has become common practice, sometimes put forth by businesses when they lobby for tax breaks from local and state governments.

But the calculations of such multipliers are often fiercely debated both in economic and political terms. For instance, the Congressional Budget Office, which calculated the impact of the 2009 federal stimulus on jobs, has set estimates that vary between as few as 1.6 million jobs and as many as 8.4 million jobs.

The accuracy of the Apple calculation may well be debated among economists for years. “Apple has a big effect, and big is about as precise as I can make it,” said Gary P. Pisano, a professor of business administration at Harvard Business School. “It’s hard to say the exact size.”

David Autor, an economics professor at the Massachusetts Institute of Technology, said via email that the “entire business of claiming ‘direct and indirect’ job creation is disreputable,” because most of the workers Apple is taking credit for would have been employed elsewhere in the company’s absence.

“But of course, they might not have been as well paid or gratified with their work,” Autor said. “We’ll never know.”

Autor also said that Apple should not be held accountable for employment problems in the U.S. “Generating the conditions that give rise to high rates of employment and wage growth is the domain of policymakers, not individual companies,” he said. “Confusing these public and private missions is probably counterproductive for all involved.”

Peter Cappelli, a professor of management at the Wharton School at the University of Pennsylvania, says companies often have a stronger case when quantifying their effects on a regional economy, rather than on the entire national economy. It does matter to a state, for example, whether a big business is there, though it might not matter nationally if the business moves to a different state, he said.

The Analysis Group, the consulting firm Apple hired, concluded that 257,000 jobs were in companies that work directly with Apple, including employees in Kentucky and New York at Corning Inc., a company that creates glass for the iPhone, and people at a Samsung plant in Texas that makes computer chips for its devices.

The Analysis Group arrived at that figure by analyzing how much Apple spent on goods and services in the U.S. in 2011 and applying that information to a formula developed by the federal government’s Bureau of Economic Analysis called an “employment multiplier.” The group used this multiplier to calculate direct and indirect employment figures from Apple’s spending, though it omitted any jobs created through spending by those people on, say, nannies, vacation homes or restaurants.

Among the outside jobs Apple said it helped support were the delivery services that bring packages of Apple devices to its retail stores and directly to customers’ homes. Norman Black, a spokesman for United Parcel Service, said the company estimated that for every 40 new packages a day transported through its system the company hired one more person. He declined to say how many packages Apple shipped through UPS and, therefore, how many jobs could be credited to the company.

“They rely on us for a lot of shipping,” Black said. “There’s no question that as they roll out and launch products, that’s creating new jobs in the U.S.”

Apple’s study said the company also supported an additional 210,000 jobs among companies creating apps for Apple devices like the iPhone and iPad. The study based that figure on the 466,000 app-related jobs that TechNet, a high-tech lobbying group, recently estimated existed in the U.S. Apple’s study estimated that 45 percent of that figure could be credited to development of software for Apple devices based on an analysis of online job listings.

While several economists and employment experts agree that Apple has an economic impact that goes beyond the people it directly employs, they said it was difficult to conclude from Apple’s study what the company’s benefit is to the overall jobs market. “They certainly have a big economic impact, as does every other firm,” Cappelli said. “If you say, ‘if there had been no Apple, those people would not have jobs,’ that’s not true.”

As an example, Cappelli said if there was no iPad, the $500 an Apple customer would have spent on the device most likely would not have been stuffed into a savings account, but rather spent on some other product or service with its own impact on employment. That impact could have been more or less than Apple’s.

Apple is, however, an innovative company that created a market for tablet computers and radically increased demand for smartphones. Apple sold more thanB 93 million iPhones and more thanB 40 million iPads in 2011.

© 2012 The New York Times Company