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Central Theorum

Decent Essays

Solution:

• No matter how carefully a production process is controlled, these quality measurements will vary from item to item, and there will be a probability distribution associated with the population of such measurements.

• If all important sources of variations are under control in a production process, then the slight variations among the quality measurements usually cause no serious problems.

• Such a process should produce the same distribution of quality measurements no matter when it is sampled, thus this is a “stable system.”

• Objective of quality control is to develop a scheme for sampling a process, making a quality measurement of interest on sample items, and then making a decision as to whether …show more content…

Procedures that would not be appropriate, at least in most institutions, would include the Whipple procedure, shunts for portal hypertension, and resection of cardiac tumors.

Several important caveats must be acknowledged with regard to the use of SQC in cardiac surgery. First, although SQC models the variability of events over consecutive time periods, it should not be confused with hazard function analysis. The latter is used to describe the time-dependent, instantaneous risk of an event after an operation, whereas SQC simply records the event as absent or present for each patient in a series of sample periods. Second, this is not a risk-prediction methodology for individual patients but rather a method of studying process variability over time. Third, except in the most general terms, it is difficult to compare this type of SQC analysis from one institution to another.
Finally, it may be argued that the CABG procedure has so much inherent variability (patient type and risk severity) compared with a manufacturing process that it is impossible to use SQC methodology. We have attempted to satisfy this objection by limiting the study to no emergent, isolated, primary CABG procedures, thus eliminating some of the most significant factors that increase

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