Validity
of Control Values
External control:
Where is the 95%
Confidence interval developed:
The manufacturer runs
the control over and over and then computes the 95% Confidence interval (± 2 S.D.). This value is then supplied along with each lot of controls and has to be specific for the instrument on which it was run.
Internal control:
The lab pools
specimens together and runs the control over
and over and then computes the 95% Confidence interval (± 2 S.D.). This is done on the same make of instrument for which the controls are being developed.