Dr. weber conducted a long-term study in which people were tested on happiness, asked to make two new friends, and then tested on happiness 1 month later. he noticed that six of the most introverted people dropped out by the last session. therefore, his study might have which of the following internal validity threats?

Attrition bias

Explanation:

When conducting an experiment, it can happens that certain participants drop out before the experiment/study comes to an end. When this happens, we say that the study might have attrition bias.

This bias is also known as sample attrition and it may affect the external and the internal validity of a trial.

In this example, 6 people dropped out before the last session of the study, therefore, we can say that this study might have attrition bias.

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