USING CONTROL CHARTS FOR QUALITY ASSURANCE

Statistical analysis is essential to quality control in the laboratory . Laboratorians use a series of numerical observations called data to provide information to the clinician. To enhance interpretation, data may be displayed numerically and graphically. Control charts have been used since the 1930s to document quality control, and their applicati ons have evolved over time. In 1981, Westgard's multirule control proc edure set forth rules to interpret control chart data in the laborator y and to indicate whether a run should be rejected and why. This is th e first in a four-part continuing education series on statistics. In t his series, we will explore four essential topics-the control chart, t he we of regression analysis, assessment of linearity, and the creatio n of reference ranges-and their use in the clinical laboratory. This a rticle will focus on the control chart and Westgard's multirule contro l procedure.