During the early development of what would become Reliability Centered Maintenance, Nowlan and Heap gave us six failure curves to the left. When folks first see that sixty eight percent fall into the infant mortality curve then the doubt fairy tends to show up. "Sixty eight percent of the failures in my facility are not instant or early on start up." With this thought they then discount the incredibly important failure mode data provided to us from these studies. What they are missing is the connection to the P-F curve below.