Abstract

The Voice of the Process (VOP) is how the process communicates with the organization on performance against customer needs and expectations. This communication takes place through process measures which are descriptors of how the process is performing in its current state. It is critical to understand how the current state is operating to define a baseline before attempting any change or improvement activities. It is important not to change a process before understanding where performance is centered or the amount of variation currently present.The most common statistical measures of a process are mean and standard deviation. Once these measures have been calculated, conducting a capability study is possible. A capability study measures the number of standard deviations between the process mean and the nearest specification limit in sigma units. In general, as a process’s standard deviation rises, or the mean of the process moves away from the center of the tolerance, fewer standard deviations will fit between the mean and the nearest specification limit. This proximity to the upper or lower limits of tolerable range increases the likelihood of items outside specification, allowing more errors to occur.