Laboratory quality control

Laboratory quality control material is usually run at the beginning of each shift, after an instrument is serviced, when reagent lots are changed, after equipment calibration, and whenever patient results seem inappropriate.

[1] Quality control material should approximate the same matrix as patient specimens, taking into account properties such as viscosity, turbidity, composition, and color.

Dried Tube Specimen (DTS) is slightly cumbersome as a QC material but it is very low-cost, stable over long periods and efficient, especially useful for resource-restricted settings in under-developed and developing countries.

The pattern of plotted points provides a simple way to detect increased random error and shifts or trends in calibration.

[citation needed] A 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.

It is named after Stanley Levey and E. R. Jennings, pathologists who suggested in 1950 that Shewhart's individuals control chart could be used in the clinical laboratory.

These rules need to be applied carefully so that true errors are detected while false rejections (of valid results that are outside of range) are minimized.