Women who begin college intending to become engineers are more likely than men to change their major and choose another career, but it’s because they lack confidence, not competence, says a paper in the October issue of the American Sociological Review.

Specifically, women lack “professional role confidence,” a term that describes, loosely, a person’s sense that he or she belongs in a certain field. The term encompasses more than mastery of core intellectual skills. It also touches on a person’s confidence that he or she has the right expertise for a given profession, and that the corresponding career path meshes with his or her interests and values.

As one of the most sex-segregated professions outside the military, engineering carries ingrained notions and biases about men being more naturally suited to the field, which can have self-reinforcing effects, notes the paper’s lead author, Erin Cech, a postdoctoral fellow in sociology at Stanford University’s Clayman Institute for Gender Research.

“The more confident students are in their professional expertise, the more likely they are to persist in an engineering major. However, women have significantly less of this expertise confidence than do men,” Ms. Cech writes, with her co-authors, Brian Rubineau of Cornell University, Susan Silbey of the Massachusetts Institute of Technology, and Caroll Seron of the University of California at Irvine.

Several recent studies, including a continuing effort at MIT, have looked at the barriers women face in engineering. The new paper adds nuance to widely held notions about what causes women to leave engineering.

Traditionally, it has been thought that women’s family plans and low regard for their mathematical skills accounted for their low representation in the field.

Ms. Cech and her co-authors found differently. Women’s family plans had little bearing on their career planning, once they entered engineering training, the paper says, though the plans probably do play a role later, when they embark on their careers. Surprisingly, the researchers found much stronger evidence that men were more likely to leave engineering if they had plans to start a family.

Women’s views of their math abilities also did not significantly predict their persistence toward an engineering degree or their intent to enter the field. “Once students matriculate into this math-intensive field, more complex, profession-specific self-assessments appear to replace math self-assessment as the driving social-psychological reasons for attrition,” the authors write.

The findings are based on longitudinal survey data of 288 students who entered engineering programs at MIT, the University of Massachusetts at Amherst, the Franklin W. Olin College of Engineering, and Smith College. The surveys were conducted in 2003, when the students were freshmen, and again in 2007, when they were seniors.

In addition to surveying the family plans and math self-assessment of prospective engineers, which have been studied elsewhere, the researchers asked how, as a result of their engineering courses, the students rated their confidence that the field was the right fit and would satisfy them.

The paper’s authors suggest that the findings about professional-role confidence may be relevant in other fields in which women are historically underrepresented, including physical science and medical specialties such as surgery.

The authors recommend that engineering programs consider engaging in more explicit discussion about professional roles, expertise, and career fit, and provide more opportunities for internships that put students into real-world engineering projects, where students can see the applicability of a broader set of skills, such as teamwork.