The process capability index $($C p $/$C pk $)$ Should be $=0\mathrm{.}5$ for a capable process the ratio of the range of values allowed divided by the range of values produced $00000$ Defines the mean and standard deviation of the process Should be $1$ for a capable process Is the mean divided by the square of the standard deviation $($variance$)$ the ratio of the range of values produced divided by the range of values allowed