Question

three graphics of control situations ( AKA Levey-jennings charts)

Answer 1

Laboratory quality control is designed to detect, reduce, and correct deficiencies in a laboratory's internal analytical process prior to the release of patient results, in order to improve the quality of the results reported by the laboratory. Quality control is a measure of precision, or how well the measurement system reproduces the same result over time and under varying operating conditions.

Interpretation of quality control data involves both graphical and statistical methods. Quality control data is most easily visualized using a Levey-Jennings chart. The dates of analyses are plotted along the X-axis and control values are plotted in the pattern of plotted points provides a simple way to detect increased random error and shifts or trends in calibration.

Levey-Jennings chart is a graph that quality control data is plotted on to give a visual indication whether a laboratory test is working well. The distance from the mean is measured in standard deviations.

On the x-axis the date and time, or more usually the number of the control run, are plotted. A mark is made indicating how far away the actual result was from the mean (which is the expected value for the control). Lines run across the graph at the mean, as well as one, two and three standard deviations to either side of the mean. This makes it easy to see how far off the result was.