Vol. 11, No. 7
July 2009
PQ Systems
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Quality Quiz from Professor Cleary

Hart Faylior and his partner Ann S.Thesia are co-owners of a small medical supply firm, In a Heartbeat Inc., that manufactures devices related to cardiac care in hospitals, including adhesive disks for EKG tests and other disposable and non-disposable supplies. Their company’s customers include hospitals and clinics as well as other medical apparatus companies.

One of In A Heartbeat’s customers, St. Recover in the Long Run Critical Care Center, is demanding capability data, and Hart has instructed Ann to examine a process for capability. They decide to work through this study together, since they have never done capability analysis for any other customer.

Process in control

Hart reminds Ann that the process must be identified as stable or in control prior to pursuing capability analysis, so she has created control charts from the data that she has, in order to check the stability of the process. She then needs to verify that the data reflects a normal distribution, by applying a chi-squared test. Ann finds that the data can indeed be considered normal, based on this test.

Data normally distributed:

After carrying out the capability study, Ann sees that the Cpk, derived with this formula, is .74. Pondering the meaning of the outcome, she tells her partner that the process is “almost 75% capable.” Examining her data and the ensuing outcome of the capability study, Hart Faylior is convinced that in light of that percentage, the process is indeed “capable enough” for this customer. Are Hart Faylior and Ann S. Thesia correct in their assessment of the situation?

a) Yes

b) No


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