interrupted time series analysis, ITS study
Interrupted time series studies attempt to detect whether the treatment has had an effect greater than any underlying trend over time.
An advantage of this study design is that it allows for investigation of potential biases in effect estimates, including trends over time; i.e. increases or decreases in a health condition with time.
For example, if a health condition is increasing before the treatment being evaluated has been administered, a before-after study would have found an increase in the outcome that might wrongly have been attributed to the treatment.
An important limitation of interrupted time series studies is that it is often difficult to be sure that the treatment occurred independently of other changes over time and that the outcome was not influenced by other confounders.
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