Descriptive term: Trend
A trend shows a gradual, continuous movement of the data values in one direction away from the mean, over time.
- A trend is indicative of a systematic error that is occurring gradually, such as with reagent deterioration, control deterioration, or a lens getting progressively dirtier.
- In the example to the right, some type of systematic error began on day 6, and by day 10, we can say that a trend has occurred and results are out of control.
- Be on the lookout for trends as they begin to take shape, and you may be able to avoid further quality control problems.
