Recent U.S. college graduates are significantly less likely to think their education was worth the expense amid concerns about growing tuition costs and student debt, according to a study by Purdue University and Gallup.

Only 38 percent of graduates who earned a bachelor's degree beginning in 2006 — compared with half of all U.S. graduates — strongly agreed that their education was worth the cost, the study found. 

Recent graduates may be more likely than older alumni to have student loan payments, and the more undergraduate debt they have, the less likely they are to say their education was worth it, the report said.

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"To some extent, older alumni might be more likely to say their education was worth it because they are further along in their careers and making more money," the report said.

Around half of public and private nonprofit university graduates also felt strongly their education was worth it, compared to 26 percent of graduates of private for-profit universities, who are more likely to have more student loan debt, the report said.

The report was based on Web surveys from 30,151 U.S. alumni aged 18 and older with a bachelor's degree or higher from all 50 states and the District of Columbia. The surveys were conducted from Dec. 16, 2014 to June 29, 2015 and results have a margin of error of plus or minus 1 percent.

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Recent graduates who had supportive relationships with professors or mentors, an internship related to their studies, participated in extracurricular activities or a project spanning a semester or more were more likely to strongly agree that their education was worth the cost, the report said.

Sixty-three percent of recent graduates said they took out student loans for their undergraduate education, with a median loan size of $30,000, according to the report.

More than a third of recent graduates took out more than $25,000 in loans, and the report said the percentage is higher among recent black alumni and first-generation college students.

The report said U.S. News & World Report school rankings are only loosely related to their recent graduates' views that their education was worth the cost.

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