Descriptive term: Shift
A shift, on the other hand, describes a sudden change in the data mean that persists throughout further days of testing.
- Shifts can be caused by any one of a number of reasons, including persistent instrument malfunction, loss of calibration, or improper reagents.
- Shifts are often easier to recognize than trends, as the data may be more clearly suspect.
- Again, shifts must be corrected as soon as possible, as patient data are most likely already invalid.
- In the example to the right, the large jump on day 8 followed by persistently high control values means that a shift has occurred.
