Dental Rates Study Group This group was established to advise on fees for items of dental treatment provided under NHS general dental services terms and conditions. The group - DRSG tie, designed by Bernard Caplan in the late 1980s, depicts the statistical test of accuracy introduced at the time to help determine the fees per item of service – relative efficiency: R2=100. The lightning flash through the ‘equals sign’ in the formula signifies that perfect accuracy was at best an inspiration. It is understood that a very small number of these ties was produced, possibly as few as ten, as part of a practical joke played on the then chairman of the DSRG.