Example 7.1 (page 182) discussed a study that found that prayer did not reduce the incidence of complications for coronary surgery patients.

(a) Just as association does not imply causality, so does a lack of association not imply a lack of causality, because there may be an alternative explanation. Illustrate this using this study.

(b) A summary of this study in Time Magazine (December 4, 2006, p. 87) noted that “. . . the prayers said by strangers were provided by the clergy and were all identical.

Maybe that prevented them from being truly heartfelt.

In short, the possible confounding factors in this study made it extraordinarily limited.” Explain what “possible confounding” means in the context of this study.