A simple interrupted time series design provides a reliable measure of the effect of the treatment because there are many observations both before and after the treatment.The major threat to internal validity in this design is
A)maturation.
B)history.
C)selection.
D)additive effect of selection and history.

Question

Quizplus · Accepted Answer

The major threat to internal validity in a simple interrupted time series design is history, as external events occurring between the pre-treatment and post-treatment observations can affect the outcome, making it difficult to attribute changes solely to the treatment.

A Simple Interrupted Time Series Design Provides a Reliable Measure