A Researcher Locates 12 Research Studies That All Examine the Effect

A researcher locates 12 research studies that all examine the effect of a different cognitive-behavioral strategy for decreasing pain-hypnosis, distraction, focusing, music therapy, and so forth. Why would these 12 studies make a poor meta-analysis?

A) Cognitive-behavioral interventions are not a suitable focus for all patients and, consequently, should not be studied.
B) Twelve studies would be too many for synthesis of any kind.
C) Secondary analyses of pooled data are not used for meta-analysis on pain, because of interindividual differences in perception.
D) The result, if statistically significant, will produce a general recommendation, "If in pain, do something cognitive-behavioral," which is meaningless.