The science of psychological measurement saw considerable development in the 20th century but has largely stagnated in the 21st. The pinnacle of the traditional approach to measurement is Item Response Theory, which was originally developed for educational testing, where it continues to be widely used. However, this approach does not fit well with mental health assessment and is rarely used for mental health instruments. The Northwestern approach is to adapt these traditional methodologies to address the unique challenges of measuring complex and often poorly defined mental health constructs.
