Three kinds of bias often find their ways into the performance review process, and they do so in ways that disproportionately affect women, Paola Cecchi-Dimeglio, a research fellow at Harvard Law School, wrote in the Harvard Business Review.

Based on data that she gathered and analyzed during a consulting project for a large global company, Cecchi-Dimeglio, who is also chair of the Executive Leadership Research Initiative for Women and Minority Attorneys at the law school, found three biases: experience bias, proximity bias, and In-group/out-group bias

These biases affect women, “especially when they choose to take advantage of the flexibility offered by hybrid and remote work,” she wrote.

Experience bias includes “overvaluing tasks that are easy to define,” she wrote. The global company she researched was undergoing a reorganization, so that its employees had to put their routine work on hold. Given this situation, Cecchi-Dimeglio found that “reviewers had judged employees ... on how they had chosen to refocus their energies.” Men, for example, “[chose] work that was much easier to recognize,” such as tasks that were highly visible or “straightforward to review when it came to short-term measures of success.” Women, on the other hand, “spent more time on much less visible internal tasks” that “had longer timelines and were harder to evaluate in the short term.”

She found that men who reviewed other men assessed them 12 percent higher than women, on average, as compared to when women reviewed both men and other women. The data indicated that men underestimated both the time a task would take and its difficulty. She then tested several interventions designed to help reviewers at the company correct this bias.  “Following the intervention, the likelihood of women accurately identifying the difficulty of the task increased by a factor of 28, while men were 12.5 times more likely to do so.” she wrote. “Additionally, men became 7 times more likely to accurately estimate the time required for a task, whereas there was no significant difference in this aspect for women.”

Another form of bias that she observed was proximity bias, “the tendency to think that people who are in your physical orbit do the most important work.”Cecchi-Dimeglio found that the hybrid work environment made it worse for women at the global company, where men were more likely than women to come into the office. “Reviewers tended to express skepticism, or at least confusion, about what women did when they worked remotely,” while giving men the benefit of the doubt and assuming that they were more focused and productive, she wrote.

To address the problem of proximity bias, she surveyed the employees to gauge their preferences among several choices. These choices included more online gatherings, an “anchor day” when everybody was expected to be in the office, or more offsite team-building opportunities. After they opted for the anchor day option, she found that the meetings helped the company resist proximity bias by drawing more equal attention to the work that everybody was doing, regardless of where they did it.

The third form of bias was that of in-group/out-group bias, which means giving preferential treatment to people in a group with whom one identifies.

Employees who worked remotely were increasingly seen as members of the out-group. Their annual performance review scores were lower by an average of 20 percent. Those in the in-group would earn benefits such as promotions and bonuses. While both sexes were subject to this form of bias, men were more easily able to join the in-group than women because they were seen more as leaders, she wrote.

To increase a sense of belonging, the company launched a campaign to increase familiarity among the employees. The experience led to a 14 percent increase in feelings of belonging to the in-group, and a 17 percent increase in employees’ perceptions of which other employees belong to the in-group. It also led to a decrease in gender discrimination in performance reviews by several percentage points.

“To include and support the best talent for your company in a dynamic environment, it’s important to take a careful look at the data, be alert to the three kinds of biases discussed in this article, and identify practices that are leading you to overvalue the efforts of certain groups,” Cecchi-Dimeglio wrote in conclusion. “The insights you gain from doing so will not only help you treat women more fairly but also will lead to fewer predictable surprises, more productive work hours, and increased efficiency in smoothly leading teams—and your company—to success.”