In the case of scratches and thickness variations, the super plastic outperforms the regular- perhaps because it is more heat resistant. There is also clearly more variation in the superplastic errors than the regular, with only bubbles being the unacceptable problem for the old system. Based on the results from the data, we need a bit more information to provide a complete analysis of the situation. We do not have data that tells us what the total runs were on the items so that we can calculate error percentage and we do not know if each error results in the same degree of cost to the company. If we assume that on an average error basis, then we can generally say that the new plastic resulted in about 25% more errors per four-week period than the old plastic....

With this preliminary data, we would conclude that it is more cost effective for the company to retain the previous material.
However, the other crucial item we do not know is the cost of the materials. If the new super plastic is far less expensive to use, then it could have a higher margin of error and still be the correct choice for the company.

There needs to be a balance based on Six-Sigma principles; where are the errors, are they correctable, how much do the errors cost the company, and can individual errors be traced to a process and fixed.

Appendix A

References

Adams, C., et al., (2003). Six Sigma Development. Burlington, MA: Butterworth.

Case Study Materials -- Delta Plastics