TABLE 3.

Covariates for PSM

Variable	Variable type	Values
Mentee’s career stage: faculty	Binary	1 = yes, 0 = no
Mentee’s career stage: graduate	Binary	1 = yes, 0 = no
Mentee’s career stage: undergraduate	Binary	1 = yes, 0 = no
Mentee’s career stage: none	Binary	1 = yes, 0 = no
Title of mentor	Categorical	1 = faculty member2 = graduate student3 = postdoc4 = researcher of scientist5 = other6 = NA
Mentor’s previous mentoring experience	Binary	1 = yes2 = no
Race/ethnicity of mentora	Categorical	1 = well represented2 = historically excluded3 = prefer not to answer
Sex of mentor	Categorical	1 = female2 = male3 = other4 = prefer not to answer
Mentor’s years of experience	Continuous

^aThe race/ethnicity variable was computed using the original racial and ethnic categories. Well-represented racial/ethnic group includes participants who reported as White or Asian, and not Hispanic. Historically excluded racial/ethnic group contains mentors who reported as any of the following racial and ethnic categories: 1) American Indian or Alaska Native, 2) Black or African American, 3) Native Hawaiian or Other Pacific Islander, 4) other, and 5) any Hispanic or Latino group.