When was Group Factor theroy by Thurstone at the University of Chicago developed?

Himachal Pradesh Staff Selection Commission (HPSSC) released the schedule of screening test to be conducted for selection to the posts of Supervisor LDR Post Code-561. Screening test was held on 28.05.2017 in evening session (from 02.00 PM to 04.00 PM). This is for ICDS department post.