Postural problems go away when the postural muscles are well supported to work easily. The best position of the postural muscles is fairly easy to find, and the process is statistically proven to be highly reliable. The result is that the seated angle of the hip and knee may vary considerably between people, but each of those people are then supported for their best strength.
The best test of validity is the report of people who have had the experience. Those people who have completed the ActivSeating recommendations report greater than an 80% average reduction in the frequency and severity of pain symptoms, and none were worse. The goal of this course is to give your people the same result.