Eighteen-year-old Anahita Nagpal’s plans to start training this fall to be a doctor are in ruins. She blames a statistical model.

Nagpal, who lives in Göttingen, Germany, had been offered a premed place and scholarship at NYU. Both were withdrawn this week, she says, after she scored more poorly than expected on her International Baccalaureate diploma, a two-year high school program recognized by colleges and taken by more than 170,000 students this year, most in the US.

Teen regrets about grades aren’t unusual, but the way the foundation behind the IB Diploma Programme calculated this year’s grades was. The results, released Monday, were determined by a formula that IB, the foundation behind the program, hastily deployed after canceling its usual springtime exams due to Covid-19. The system used signals including a student’s grades on assignments and grades from past grads at their school to predict what they would have scored had the pandemic not prevented in-person tests.

Nagpal and many other students, parents, and teachers say those predictions misfired. Many students received suspiciously low scores, they say, shattering their plans for the fall and beyond. Nagpal’s backup plan if she missed out on NYU was to study medicine in Germany, but her lower-than-expected grades don’t allow that either. “Like so many, I was extremely shocked,” she says. “I basically cannot study what I want to anywhere anymore.”

More than 15,000 parents, students, and teachers have signed an online petition asking IB to “take a different approach with their grading algorithm and to make it fairer.” The foundation declined to answer questions about its system but said it had been checked against five years of past results and that disappointed students could use its existing appeals process, which comes with a fee. The foundation released summary statistics showing that this year’s average score was slightly higher than last year’s, and it says the distribution of grades was similar.

One math teacher at a school in the Middle East says IB should disclose the full workings of its model for outside scrutiny. He and a colleague with a math PhD have been puzzling over its design since several students lost scholarships to top universities, after receiving results much lower than expected by their teachers. Some students caught out are now unsure how they’ll pay for college. “My only guess is a flawed model,” he says.

Concerns about flawed math models are growing as more companies and governments apply computers to traditionally human problems such as bail decisions, identifying criminal suspects, and deciding what is hate speech. Rooting out bias and inaccuracy in such systems is a growing field of activism and academia.

People questioning IB’s algorithm-derived grades are now raising some of the same issues. They’re wondering how the system was designed and tested, why its workings weren’t fully disclosed, and whether it makes sense to use a formula to determine the grades that can shape a person’s opportunities in life.

When Covid-19 seized hold of the world in March, many teens in their final year of high school were left in a precarious position. Shelter-in-place orders made it challenging or impossible to complete the final assignments or tests that could determine their college and life choices.

Test providers scrambled to devise new ways to assess students. In the US, Educational Testing Service, which provides the GRE, and the College Board, which runs AP Exams, moved their tests online. That brought quirks and glitches—like requiring students to take their tests simultaneously regardless of time zone and retakes forced by technical errors—but it maintained a semblance of the normal process.

IB, headquartered in Geneva, opted to use a statistical formula instead—adding to the growing list of tech fixes proposed to automate away fallout from the pandemic. The workings of the IB diploma—and the timing of the results—proved particularly harmful for IB students applying to US colleges. Unlike AP tests, which are typically separate from high school grades, the IB results are intended to reflect a student’s work for the year. IB students are often granted college admission based on predicted grades, and they submit their final results when they become available over the summer. Some colleges, including NYU and Northeastern, warn on their admissions pages that students whose IB results don’t get close enough to those predictions may lose their place.

In normal times, IB diploma students select six subjects, from options such as physics and philosophy, and receive final grades determined in part by assignments but mostly by written tests administered in the spring. The program is offered by nearly 900 public schools in the US and is common in international schools around the world. In March, IB canceled all tests and said it would calculate each student’s final grades using a method developed by an unnamed educational organization that specializes in data analysis.