In an article on the method, psychologist Hill Walker, a professor at the University of Oregon who had studied behavioral disorders in schoolchildren for 34 years told Wired Magazine, "There are some serious validity issues here, some reputation-ruining implications [REF]."
De Becker responded that MOSAIC for Assessment of Student Threats (MAST) is never applied to the general population of students, and rather just to those students who self-identify by making a threat [REF].