The reliability of subjective vehicle evaluation

Vehicle evaluation is an important tool for the development engineer, whether as a means of interpreting measured results or of analysing and understanding customer preferences and criticism. However, like any other measuring instrument, the evaluator has to calibrate this data output and analyse error sources. The student's t–test shows at a glance how accurately a group of evaluators can do the job. To cater for product quality variation the student's t–test formula is extended by a correction factor. Thus a relatively quick method of analysing evaluation data with respect to accuracy range and reliability is now available.