In a time series design,the series of observations before treatment helps reduce threats to internal validity because
A)a series of observations is more reliable than a single observation.
B)a series of observations has more validity than a single observation.
C) if an outside factor is influencing the scores,the effects should be seen before the treatment is administered.
D) if an outside factor is influencing the scores,it can be stopped before the treatment is administered.

Question

Quizplus · Accepted Answer

One of the main threats to internal validity in a time series design is history, in which an outside factor may influence the scores of the dependent variable. By having a series of observations before treatment, any effects of these outside factors should be visible in the data. This helps to establish a baseline and control for any potential confounding variables. Therefore, choice C is the best answer. The other options (A, B, and D) do not address the specific threat to internal validity posed by history.

In a Time Series Design,the Series of Observations Before Treatment