A researcher conducted an experiment to test a new cognitive therapy for post-traumatic stress disorder.After 6 months of administering the therapy with his clients,the researcher found that 75 percent of his clients got better.He proclaimed the new therapy successful.What was wrong with this study?
A) There was no dependent variable.
B) There was no placebo group.
C) He did not use a representative sample.
D) Six months is too short a time to evaluate the effectiveness of therapy.

Question

Quizplus · Accepted Answer

The study did not have a placebo group, which is an essential component of a randomized controlled trial, to rule out the possibility that the clients' improvement was due to a placebo effect or other extraneous factors. Therefore, it is not possible to conclude that the therapy itself was the sole cause of the clients' improvement.

A Researcher Conducted an Experiment to Test a New Cognitive