Field reliability versus predicted reliability: An analysis of root causes for the difference

Thirty-eight reliability experts from the US Department of Defense (DOD) and industry were asked to identify and rank order factors which potentially contributed to the difference between actual and predicted reliabilities (referred to as the reliability delta). Total quality management (TQM) tools were used to analyze the relationships among and impact of key variances on the reliability prediction process and explain apparent differences between the DOD and industry perspectives. The literature review identified eleven factors as possible causes of the reliability delta; however, only six were noted as being significant by the experts. The six factors identified were: problems with data collection; assumptions underlying and use of prediction techniques; lack of understanding of the operational environment; problems with manufacturing processes; short-term management focus; and design-related problems