Optimal standard measures: Comment on Matthews et al. (2016)

Matthews, Adler, Forrest, and Stead (2016) implied that measures of mental health constructs such as depression can be made interchangeable by standardizing their scores. The present author contends that content differences in the measures a priori prevent their equivalence and that, instead, we need to agree on a standard definition of the construct and then use only a definition-fitting optimal standard measure.