(Bloomberg News) College students' choice of major can mean the difference between median earnings of $120,000 for petroleum engineering and $29,000 for counseling psychology, a study by Georgetown University showed.

Of the top 10 undergraduate majors with the highest median salaries, eight were in engineering, including aerospace, chemical and mechanical, according to the study released today by Georgetown's Center on Education and the Workforce.

Many of the least popular majors, including naval architecture and marine engineering, command among the highest pay, while some popular subjects -- elementary education and psychology -- generate some of the lowest, according to the report. While a bachelor's degree holder can expect to earn 84 percent more over a lifetime for full-time work than someone with only a high school diploma, a student's major is correlated to income, said Anthony P. Carnevale, director of the center.

"It's not the way most people see college," Carnevale said in an interview from Washington. "Most people think it's about getting a degree," rather than what you major in, he said.

Researchers categorized 171 undergraduate majors into 15 groups including health, humanities and liberal arts, and law and public policy. They analyzed data from more than half a million respondents to the U.S. Census Bureau's 2009 American Community Survey, who reported their undergraduate major and how much they earn. All were between the ages of 25 to 64.

As a group, engineering majors of all disciplines reported the highest median earnings at $75,000, the study showed. The lowest pay, at $42,000, came from two groups -- education and psychology and social work, which includes such categories as clinical psychology and communications disorders.

Race, Gender

Race and gender play a role in salary, according to the report. African-Americans who graduated with finance majors earned an average of $47,000 per year, less than Hispanics and Asians at $56,000 and whites at $70,000, it showed.

While women hold the majority of degrees in many lower-paying fields, even those with specialties that command the highest pay, such as chemical engineering, earned $20,000 less per year on average than men with the same education, according to the study.

About 25 percent of respondents reported majors in the business group, which had 13 subcategories, including finance, accounting and marketing. Those with a degree in business economics had the highest median earnings -- $75,000. That compares with the $70,000 median for an economics degree in the social science group.

About 41 percent of undergraduates with humanities and liberal arts majors -- including history, English language and literature and foreign languages -- went on to earn a graduate degree, the study showed.