A metal fabricator produces connecting rods with an outer diameter that has a $1+-\mathrm{.}01$ inch specification. A machine operator takes several sample measurements over time and determines the sample mean outer diameter to be $1\mathrm{.}002$ inches with a standard deviation of $\mathrm{.}003$ inch.

Calculate the process capability index for this example. $($Round your answer to $3$ decimal places.$)$

Process capability index