ABSTRACT
Thus far, we have focused our attention on determining whether a process is in statistical control or predictable. In this chapter, we deal with another important question — Is the in-control process capable of producing products that meet the specifications of the customers? After a process has been stabilized, the behavior of the process defines its capability. It is important to understand that a process in statistical control will not necessarily produce units that meet the specifications established by the customer. Any attempt to improve a process must be preceded by a process capability study. The following scenarios highlight the significance of process capability studies:
Suppose a hospital that belongs to a major healthcare system receives a mandate from the corporate office to reduce the waiting time in the emergency room from its current level of 4 hours (for acuity level 3) to 2 hours. If the process is statistically in control, is the emergency room capable of “producing” to that specification?
