Using cognitive pretesting in scale development for Parkinson's disease: the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) example.
Tilley BC, LaPelle NR, Goetz CG, Stebbins GT. Using cognitive pretesting in scale development for Parkinson's disease: the Movement Disorder Society Unified Parkinson's Disease Rating Scale (MDS-UPDRS) example. J Parkinsons Dis. 2014; 4(3):395-404.