As high school seniors across the United States fill out college applications, many will run a cost-benefit analysis of the cost of a school against the lifetime earnings potential of a degree from there. But that is not the only consideration.

Georgetown University's Center on Education and the Workforce (CEW) regularly calculates the value of college degrees — which schools and areas of study offer the best potential return in the form of career earnings.

The center recently released "Ranking Your College: Where You Go and What You Make." Reuters asked CEW Director Anthony Carnevale to explain how future earnings potential should affect a college choice.

Q: Is the school the most important factor when it comes to future earnings?

A: It's not so much the college that matters, it's what you take. What is most startling is the difference by field of study.

If you go to college you will make, on average, $1 million more over your lifetime than someone who graduated from high school.

But if you were someone with a degree in (energy-based) engineering, you would get $5 million more.

Q: Are there any scenarios in which the average earnings potential alone is not enough to justify the cost of attending a certain school?

A. In 80 percent of the cases, earning a bachelor's degree or better is worth it.

About 20 percent of the time, people with college degrees earn no more than people with high school degrees. That has more to do with field of study.

Those who study arts and humanities, psychology, education … tend to earn less. And there's a wide distribution of earnings over the years. Some graduates end up at the bottom of the earnings distribution.

Q: Perhaps it is no surprise to see schools like Harvard University ($87,200) and the Massachusetts Institute of Technology ($91,600) at the top of the earnings potential list. But what about the U.S. Merchant Marine Academy ($89,000) and Massachusetts Maritime Academy ($79,500)?

A: Curriculum affects earnings. Maritime academies are career-based institutions. They give strong occupational preparation and strong academics. And when you go to sea, you make a ton of money.

Q: How big of an effect does receiving a graduate degree have on earnings potential?

A: It's mostly positive. There are some of them that are dogs.

Professional degrees are strongest over all. If you are an education major or psychology major, you really need to go to graduate school.

Q: If a college with low earnings potential is picked, is the student doomed to a life of limited income?

A: What you're talking about is an aggregate number. If you go to a school where the overall earnings potential is very low, it may be that the school has a very low graduation rate. Or it could be a school where very few have gone on to graduate school. There are some schools that have 50 percent education majors.

Q: Does the data show what impact returning to school midcareer has on earnings potential?

A: For them, field of study is everything. Older students are very good at picking a field of study. They are very career oriented.

Mitch Lipka writes for Reuters.