Which one of the following statements is most true concerning baseline stability in an interrupted time series design? It is desirable to have
A) baseline stability before the independent variable is introduced
B) baseline stability after the independent variable is introduced
C) baseline stability before and after the independent variable is introduced
D) abrupt changes in baseline before the independent variable is introduced

Question

Quizplus · Accepted Answer

Baseline stability is important for ensuring that any observed change in the outcome variable is due to the independent variable and not some other extraneous factor. It is desirable to have baseline stability both before and after the independent variable is introduced so that any change in the outcome variable can be attributed to the independent variable. Abrupt changes in baseline before the independent variable is introduced may suggest that some confounding variable is influencing the outcome variable, so this is not desirable.

Which One of the Following Statements Is Most True Concerning