Arlington-based CEB is one of the world’s largest providers of online talent tests. This clip shows a sample of what test takers see when they encounter the company’s 3-D animated avatars. (Courtesy CEB)

If you’re applying for a job as a customer service representative at T-Mobile, you’re bound to encounter Jason Easton, a cranky mock customer who has been on hold for nearly an hour.

“Ah! It’s about time,” he says, demanding to know why his bill has gone up.

As Easton rattles off his name and phone number, you’ll have to quickly pull up his account, help him with his bill and determine whether he’s eligible for a $30 credit that he wants.

T-Mobile asks job applicants to take this test before inviting them for an interview because the company has found powerful correlations between the online assessments and success on the job. High scorers tend to resolve customer calls about 25 seconds faster than those who receive low scores. That means they can handle one more call a day and about 250 more a year.

At T-Mobile and legions of other companies, Web-based tests have become a key gateway to landing a job, a potent screening tool that can effectively bump a résumé to the top or bottom of a manager’s pile.

Companies are using these tests to evaluate skills and personalities for job openings at every rung of the career ladder, from bank teller to C-suite executive. They are not merely on-screen versions of decades-old paper employment tests. They are built on the power of big data: Creators have harnessed a massive trove of results to help companies pinpoint the kind of worker who might thrive in a particular job.

Test makers say their offerings bring a consistency and objectivity to a process that can sharply improve the odds of hiring the right person. But in a highly competitive job market in a tepid economic recovery, the increased use of online testing could mean that workers who aren’t digitally savvy or lack Web access might face one more hurdle in getting a job.

“Assessments are right more often than they’re wrong,” said Elliot Clark, chief executive of SharedXpertise Media, a firm that puts on conferences for the human resources industry. “But like anything else, when you do a prediction, the forecast has a percentage of accuracy. The issue is: What percentage of people get screened out that should have gotten a shot?”

CEB, an Arlington-based company that is among the world’s largest providers of such tests, says it is administering 30 million talent tests a year — one for almost every second of every day. Another online test provider, IBM, says it administers 36 million assessments a year, most of which are pre-employment tests.

In 2013, more than a third of new hires reported taking such a test, compared with 18 percent in 2008, according to CEB data.

Some tests evaluate a specific skill, such as how quickly and accurately someone can make change from an onscreen cash register or program software in the Java coding language. Many tests incorporate simulations of scenarios one might encounter on the job. Marriott International, for example, shows housekeeping applicants a photo of a landscaped area at one of its hotels and asks candidates to determine what’s wrong with it. (Perhaps a gardening tool was not put away properly). In one of CEB’s tests for a supervisory role, applicants might have to demonstrate how they would talk to an employee who was coming in late and missing important meetings.

Providers say the tests hold the promise of leveling the playing field for job applicants by removing the chance of bias that comes with a traditional résumé screening. The tests can’t distinguish, for example, if a candidate didn’t attend a top-tier college, is currently unemployed or is a woman or minority.

“In many cases, algorithms can trump instinct on staffing,” said John Boudreau, a professor in the business school at the University of Southern California, adding that decades of research have found that tests can serve as reliable barometers of certain personality traits, such as conscientiousness.

Experts say this type of testing is on the rise now because innovations in technology have made the assessments markedly simpler to administer while improvements in data analysis have made them more useful. The software also helps hiring managers sort through the ever-growing volume of résumés they receive, as the application process increasingly moves online.

T-Mobile, for instance, received about 1 million job applications last year in the United States and hired about 14,000 people. Jared Flynn, head of talent acquisition at the wireless company, said the tests have become a crucial part of the hiring process for store associates, managers and call center representatives. Although hiring decisions are ultimately made based on a combination of test results and interview performance, Flynn says, managers will look first to the “top of the barrel”—in other words, those who scored best on the tests.

“This saves a third to half of the recruiting labor. It’s huge,” Flynn said.

For T-Mobile sales associates, data show that those with high test scores bring in more revenue per hour and that the customers they assist have lower rates of service cancellation. Meanwhile, those who performed poorly on the T-Mobile assessment were twice as likely to quit a job, which can cost the company thousands in hiring and training expenses.

To make the simulations as realistic as possible, CEB uses professional voice actors and bases the movements of its 3-D animated characters on those of a person in a motion-capture suit.

At IBM, which makes tests as part of its Smarter Workforce initiative, Zahir Ladhani, a vice president, said the assessments help companies hire better salespeople by making them rethink assumptions about the kind of person who will thrive in that role.

“The perception out there is [you need] outgoing and persuasive,” Ladhani said. “But our studies show you want somebody who’s sensitive and helpful.”

Josh Bersin, principal of the human resources consultancy Bersin by Deloitte, said his firm estimates that employment testing is a $1 billion market.

“They’re very, very good things for both sides,” Bersin said.

Still, Web-based tests might present obstacles for some workers.

Many of CEB’s tests, for example, cannot be taken on a mobile device. That is by design, because the company’s research has shown that people score lower on cognitive ability or problem-solving tests when they’re taken on mobile devices. CEB is trying to figure out why. One hypothesis is that people who use mobile devices are taking the tests while on the go and, therefore, distracted.

“As scientists and as ethical professionals, we’re keeping the brakes on it a little bit,” said Ken Lahti, CEB’s vice president of product development and innovation.