Yale students who are taught by tenure-track professors may learn less than students taught by lecturers, according to a new study.

According to a September 2013 report published by the National Bureau of Economic Research that considered data from 15,000 Northwestern University students over eight years, students who took introductory courses taught by tenure-track professors learned less than students who took the same class with a non-tenure-track professor — the Yale equivalent of a lecturer. The researchers measured how much a student learned by evaluating two criteria: first, how likely the student was to take another class in that subject, and second, how well the student performed in that subsequent class. Non-tenure-track faculty outperformed tenure-track faculty in both respects.

“My collaborators and I didn’t know what to expect when we embarked on this project, because we could formulate highly plausible hypotheses that could predict [multiple outcomes],” study author David Figlio, said in an email.

Figlio said he was not surprised by the study’s results, as tenure-track faculty are measured and evaluated by the quality of their research, while non-tenure-track faculty are “recruited, retained and rewarded” for the quality of their teaching. This may cause them to be more focused on their students than their tenure-track counterparts, he said.

Economics Director of Undergraduate Studies Samuel Kortum said that though he has not read the study, its findings are fairly predictable.

“I’m not denying or surprised that a study says that people at least like the courses taught by non-[tenure]-track teachers better,” Kortum said.

Economics professor and recent Nobel Prize winner Robert Shiller has been criticized by some students for his lecturing style in his “Introductory Macroeconomics” class this semester. But Kortum defended Shiller’s teaching, saying that a tenured professor might have a lot to offer even if students do not find him to be the smoothest lecturer.

Kortum said he is also wary of teacher evaluations, because the likability of a professor may not be an accurate reflection of the experience he or she can give students.

Doug McKee, associate chair of the Economics Department, said he agrees with Kortum that there is merit to having tenured-track faculty members teach introductory courses, which he pointed out is a long-standing tradition at Yale. He said that introductory courses not only give students background knowledge, but also encourage them to take more classes in the department. For this reason, he said, it is important for students to have exposure to the top researchers in the field — the tenure-track professors.

Amen Jalal ’17 said it is precisely Shiller’s research experience that makes him an effective teacher. Because he has so many personal stories about how he has actually applied the material, the course becomes more relevant and interesting, she said.

“Generally when you study textbook material, you don’t know how to relate it to the world,” Jalal said. “But when Shiller talks about stuff he’s done or talked about at conferences, you realize it’s much more practical. I’ve personally always enjoyed his anecdotes more than anything — I can read the textbook on my own.”

The study acknowledged that it did not measure tenure-track faculty’s teaching quality for more advanced courses. Mevlut Ikiz ’17, a student in Shiller’s class, said the basic course content in “Introductory Macroeconomics” could be the root of his dissatisfaction with Shiller’s teaching.

Figlio said the study was not intended to guide administrators to assign faculty to certain courses. Rather, he said, it was meant to be an objective statistical analysis of instructional quality — but the results may still have real implications for the academic world.

There are 459 tenured Arts and Sciences professors at Yale College, according to the University’s website.