A flood of students unexpectedly accepted admission offers. A University of California campus was caught off guard. Administrators scoured the files of the admitted and took a hard line on those who had failed to meet paperwork deadlines. They withdrew more than 500 offers, causing a furor.

The year was 2015, the campus Santa Cruz.

The storm that UC Irvine recently unleashed when it took a similar approach to overenrollment was unusual but hardly unheard of on the nation’s college campuses. Experts say the two UC cases and others like them at Temple University in Philadelphia and St. Mary’s College of Maryland underscore the vagaries of enrollment prediction — a discipline that aims to meld the science of data analysis with the guesswork of anticipating teenage whims.

Cal Poly San Luis Obispo also miscalculated its numbers this year, with about 700 more students saying yes to its offers than expected. One curveball was a campus decision to eliminate the option for students to make an early, binding commitment to enroll, which boosts their chances of admission but was seen as advantageous to the wealthier ones who did not need to wait for financial aid packages.

(Next: What universities are doing about enrollment prediction)


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