In the Thom Et Al

Multiple Choice

In the Thom et al. (2000) study of the treatment of dental-phobic patients, if participants in the two experimental groups showed reduced anxiety from pretest to posttest, could the researchers conclude that the treatments were effective in reducing anxiety?

A) Yes. Reduction in anxiety for the experimental groups would prove the effectiveness of the treatment.
B) No. There are many possible reasons why patients would show reduced anxiety, so the only way to know if the cause was the treatments would be to use a control group that did not get a treatment.
C) Yes, but only if one of the groups had a greater reduction in anxiety than the other.
D) No. To conclude that the treatments were effective, they would need to see if the effects last for many years afterwards.