From 'funny time, funny money' to realistic labour times

The motor vehicle retailing and services industry is one of the largest service industries in the developed world. A persistent issue concerning consumers, motor vehicle insurers, and smash repairers alike is how much a smash repairer should be paid for the paint labour time. While attempts are being made to replace the old system known in the smash repairs industry as 'funny time, funny money' by fairer systems based on empirical evidence, there is lack of rigorous analysis based on observed data and sound statistical methods. This paper proposes and calibrates a statistical model for estimating paint labour times, accounting for the inherently significant uncertainties in the paint process. Fine details such as flash-off time, the number of paint layers, and the number of coats per layer are included in the model. A series of experiments were conducted at various paint workshops over a few years to collect data for model calibration. It was found that, excluding drying time, paint labour times obey a simple relationship to the panel areas. A case study was performed to compare the model predicted upper bounds with an empirically developed commercial system of paint labour times.