Comment on Demographic gaps or preparation gaps?: The large impact of incoming preparation on performance of students in introductory physics

A recent paper by Salehi et al. claims that the differences found between major demographic groups on scores in introductory college physics tests are due to differences in pre-college preparation. No evidence is produced, however, to show that preparation differences are more causally important than any other differences. In one case, the male/female difference, the paper actually provides evidence that preparation gaps are unimportant.