The master’s degree business is booming. College graduates looking for a leg up in the job market are flocking to one- and two-year programs that promise entry to lucrative careers. Top colleges are more than willing to provide them — for a price. Tuition for a 30-credit master’s in computer science from the University of Southern California runs $57,000. Syracuse, Johns Hopkins and Carnegie Mellon charge over $43,000 for the same degree.

But one highly ranked program, at Georgia Tech, has taken a very different approach. Its master’s in computer science costs less than one-eighth as much as its most expensive rival — if you learn online. And a new study by Harvard economists found that in creating the program, Georgia Tech may have discovered a whole new market for higher education, one that could change the way we think about the problem of college costs.

Georgia Tech rolled out its online master’s in computer science in 2014. It already had a highly selective residential master’s program that cost about the same as those of competitor colleges. Some may see online learning as experimental or inferior, something associated with downmarket for-profit colleges. But the nation’s best universities have fully embraced it. Syracuse, Johns Hopkins, U.S.C. and others have also developed online master’s degrees, for which they charge the same tuition as their residential programs.

Georgia Tech decided to do something different. It charges online students the smallest amount necessary to cover its costs. That turned out to be $510 for a three-credit class. U.S.C. charges online students $5,535 for a three-credit class. (Both programs also charge small per-semester fees.)

With one of the top 10 computer science departments in the nation, according to U.S. News & World Report, Georgia Tech had a reputation to uphold. So it made the online program as much like the residential program as possible.

Charles Isbell, a senior associate dean at the College of Computing, helped lead the effort. Mr. Isbell has a Ph.D. in artificial intelligence and machine learning from M.I.T., and he teaches those subjects at Georgia Tech. He translated his lectures into well-produced online videos while administering the same homework assignments, midterms and final exams. Tests are proctored by a company that locks down a student’s computer remotely and uses its camera to check for cheating.

In theory, on-campus programs offer direct access to professors and peers. Mr. Isbell began noticing differences in that respect between his residential and online students. He was interacting much more with students who had never set foot on the Atlanta campus.

“I never see students at my office hours,” he said. A few linger after class to ask scheduling questions, but that’s about it.


Charles Isbell at Georgia Tech in Atlanta this week. A senior associate dean at the College of Computing, he helped lead the university’s online education effort. CreditJessica McGowan for The New York Times

Many of the thousands of online students, by contrast, are constantly interacting on a website set up for that purpose, where Isbell can log on and help. “I can jump in and say: ‘No, you should be thinking about this,’ ” he said. “I spend more time helping them with assignments online than I ever do on campus. The experience for the students and for me is much richer online.”

The on-campus program enrolls only 300 students or so, nearly all top students from other countries. It isn’t easy to find room for more. Lecture halls and classrooms are expensive, and competition between departments for space is fierce. The online program has nearly 4,000 students, the large majority American. Many have organized study groups in their home cities. At that scale, there is almost always someone else online, day or night, to talk to about a thorny problem in machine learning.

The combination of a prestigious department, traditional degree and drastically lower price was something new in American higher education. Economists Joshua Goodman of Harvard, Julia Melkers of Georgia Tech and Amanda Pallais of Harvard decided to study the program. They were interested in whether Georgia Tech was simply recruiting students who would have enrolled elsewhere — or if the program was creating something new.

Fortunately, a quirk in the program created a kind of natural experiment. In the first year, Mr. Isbell and his colleagues didn’t want to be overwhelmed by students while working out the inevitable kinks. So they ranked the applicants by their undergraduate grade point average and cut off admission at 3.26, yielding 500 students. Mr. Goodman and his colleagues compared the students just below the cutoff with those just above. Using a national database of college enrollment, they investigated where the rejected students enrolled instead.

Overwhelmingly, the answer was nowhere.

Barely 10 percent chose a different program. The vast majority simply didn’t pursue a master’s degree at all. The demographic profile of the online students shows why. The traditional on-campus students in the Georgia Tech master’s program tend be young and just out college, with an average age of 24. The average age of the online students was 35. A sizable number were 45, 50 and older. Ninety percent were currently employed.

People with jobs and families can’t just pull up stakes and move to Atlanta or Los Angeles for a year or two to study computer science. Nor can they afford to spend $57,000 out of pocket for a credential. Georgia Tech offered a prestigious, high-quality computer science program that was convenient and affordable. It was the only one.

Questions of technology and affordability in higher education have been dominated in recent years by so-called Massive Open Online Courses, or MOOCs. The Georgia Tech program grew out of a partnership with a MOOC company, Udacity. But while many MOOCS are offered by well-known universities, they don’t lead to a traditional credential like the master’s degree. (EdX, a MOOC consortium led by Harvard and M.I.T., recently started a series of “MicroMasters” programs.)

MOOCs are also usually free. The Georgia Tech program isn’t free, because it costs money to oversee the courses and hire teaching assistants to grade homework assignments and exams.

The Harvard study suggests there is a vast untapped market for highly affordable degrees from prestigious colleges. The technology needed to build those programs exists today. But most prestigious colleges are currently sticking with the model that lets them offer degrees for $57,000 instead of the roughly $7,000 that it costs at Georgia Tech.

This year’s presidential campaign has featured a robust debate about the cost of higher education. Hillary Clinton has proposed an ambitious and expensive plan to lower the price of college by subsidizing public institutions and lowering interest rates on outstanding student debt. But unless these policies are accompanied by strong incentives for colleges to be more like Georgia Tech, the college cost problem will remain.