In 2014, the average tuition for certificate students at for-profit colleges was $8,118, compared to $712 for community college students.

The Washington Post reports.

A popular college investment promised students a career, but didn’t pay off

Students who earned vocational certificates from for-profit colleges made an average of $900 less annually after attending the schools than they did before, according to a new study, leaving those who took out loans hard-pressed to pay them back.

By contrast, demographically similar students who received the same certifications from public community colleges earned $1,500 more than they did before attending school.

The paper from the National Bureau of Economic Research, published this week, offered new evidence for critics who say the for-profit college industry swindled students by pressuring them into racking up tens of thousands of dollars in debt while adding comparatively little value to their careers.