Providers of diversity training almost uniformly report that fear of litigation is the primary reason companies contact them. But since the mid-2000s, there has been a small-but-growing shift in thinking among corporate managers: More diversity in the workplace — in experience, race and sexual orientation — makes for a .more competitive business.

This movement was perhaps best expressed in the 2008 book “The Difference,” by University of Michigan professor Scott E. Page. In it, Page used mathematical analysis to show a relationship between greater diversity and group achievement.

“If you have a homogenous group of people with the same background, it’s harder for them to solve a problem,” says Nick Witenberg of Optimism Matters, a diversity trainer based in Atlanta. “Racial, generational and cultural diversity brings different schools of thought to the table, so they can come up with an idea more quickly and implement it better.”

Dr. Derek Avery, a professor of Human Resources Management at Temple University and an expert in diversity analysis, disputes the statistical methods used in “The Difference,” but not the general premise of the book. “I think the best part of books like this is that it makes people question their assumptions,” says Avery. “I once asked an executive about her views on diversity, and she said, ‘People who say that you shouldn’t be diverse have some pretty narrow assumptions about what all the best people look like.’ I think that’s pretty much the best way to put it.”