System Boundaries

Note that this conclusion is associated with a lower standard of evidence because it was based on a fractional factorial array-based method rather than a two sample t-test and the so-called individual error rate (IER) was used Yet, most importantly, it was immediately confirmed that adjusting shot size to the high level effectively eliminated the sticking problem. The effect was proven and confirmed.
The other potentially important factors included E (chamber humidity). The result for chamber humidity was surprising. This factor is not found to be significant using the Lenth hypothesis test but the posterior probability suggests
that it might be important. The expensive “hydrolyzer” machine had been bought precisely to help eliminate the sticking problem. It created another step in the process before the injection of the rubber. Yet, the results indicated that there was a
non-negligible probability that the hydrolyzer was actually making the problem worse, i.e., increasing the % not sticking.