ABSTRACT
Voltage regulators fitted to private motor cars were required to operate within the range of 15.8 to 16.4 volts, and the following investigation (Desmond, 1954) was conducted to estimate the pattern of variability encountered in production. The normal procedure was for a regulator from the production line to be passed to one of a number of setting stations, where the regulator was adjusted on a test rig. These regulators then passed to one of four testing stations, where the regulator was tested, and if found to be unsatisfactory, it was passed down the production line to be reset. For the data of Table S.1, a random sample of four setting stations took part, and a number of regulators from each setting station were passed through each testing station. One special aspect of interest concerned the percentage of regulators that would be unsatisfactory were the mean kept constant at 16.1.
