"It seems that the vast majority of students wanted a summer job," Badaracco said. "We thought students would take advantage of a faster way to get through the program, but with the economy so strong, students seemed to put more value in the opportunity to try something new during the summer."

HBS introduced the two-cohort system in 1994 for three primary reasons, according to Badaracco.

First, professors would have more opportunities to experiment with teaching methods.

"You could try something and see how it worked, and try again without having to wait a whole year," Badaracco said. "The cycle time was reduced dramatically."

Also, the smaller size of the January cohort allowed for smaller instruction groups.

Admissions criteria were the same for students in both cohorts. Students were asked to select their preferred entrance date in their applications.

As a result of the experimentation facilitated by the two-cohort system, Badaracco said, several innovative programs were introduced.