Web-based tools are provided to illustrate the calculations and graphs that are useful for different sets of experimental data. This lesson describes how to use statistical parameters to estimate the specific types of errors of interest in a method evaluation study. It focuses mainly on the comparison of methods experiment where the interpretation is most difficult. This lesson provides the key to making rational decisions about method performance, which is to compare the estimates of analytical errors with the amount of error that is allowable. If the observed errors are greater than the allowable error, method performance is not acceptable.
Acceptable performance requires that the observed errors be smaller than the allowable error.
In QC - The Idea, Dr. Westgard describes the basic approach for monitoring the variability of a method and identifying those situations where test results exceeds the variation expected under normal operation. Dr. Sharon Ehrmeyer reviews the USA laboratory regulations and accreditation guidelines that influence current QC practices. A summary table of clinical decision levels is provided courtesy of Dr. Bernard Statland. A cholesterol example is used to illustrate the calculation of control limits, plotting of control ponits, and interpretation of results. Dr. Westgard explains the reasons for the different numbers of rejections by the different control rules in the lesson QC - The Chances for Rejection.