In Interventional Research, Why Does Subject Attrition Affect Internal Validity

question 39

Multiple Choice

In interventional research, why does subject attrition affect internal validity?

• A)A study in which the majority of the subjects die calls into question whether the treatment itself is safe.
• B)Subjects who drop out may differ from those who stay in the study, in terms of an important extraneous variable.
• C)If subjects drop out of the control group, and not the experimental group, it strongly implies that there is some benefit to participation of which the researchers may not be aware.
• D)Subject mortality may result in a sample that is so much smaller than anticipated that Type II error may result.
• E)Type I error is almost guaranteed with very unequal sample sizes.

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