Group Rate Levels in Workmen's Compensation Insurance

Prior to the introduction of group rate levels into the Workmen's Compensation rate making plan, there was no necessity for calculating the change in rates by industry group. Whenever a test of proposed rates was made, it was deemed sufficient to make a test of the aggregate change in rates. Although such tests did not reveal it, the average rate changes for the individual industry groups must have departed considerably from the average rate change of all groups combined, as a result of varying relativity among individual classifications. Since the introduction of group rate levels into rate making, attention has been focused on the rate changes by industry group. The question naturally arises how much do group rate levels alter the rate changes by industry group?