skill or talent of the healer cannot be quantified in the same way that experience (e.g., number of patients treated) can. The problem is more complicated yet when treatment effectiveness is presumed to depend on a particular relationship, rapport, or bond between the patient and the healer. Unless that relationship or rapport can be defined and assessed at the start of a research trial, there is a risk that a poor outcome will be used as evidence that the necessary relationship did not exist and a good outcome will be used as evidence that it did.

For many CAM therapies, there is a need to pay explicit attention to placebo or expectation effects. In most studies in conventional medicine that include a placebo control arm, the goal of the study is to show that the treatment in question is superior to the placebo. The underlying assumption is that a placebo effect is not real biologically and that the treatment being studied can be deemed to have an effect only if the outcomes that result from the treatment are significantly better than those from the placebo. In many CAM modalities (and in some conventional medicine modalities as well), however, the placebo effect is an inherent part of the mechanism of treatment efficacy. That is, the benefit obtained by the patient is at least partially due to his or her own sense of hope, positive expectation, and activation of self-healing processes. One cannot design a study to eliminate these processes as explanations for outcomes, since they are, by definition within the CAM modality, not a source of noise or confounding but part of the essence of the treatment itself.

In evaluations of CAM therapies, end points may be difficult to measure in a standardized way. The techniques used to measure subjective experiences like pain, fatigue, the ability to perform daily activities, and mood state have experienced significant advances in the past 20 years (IOM, 1999). CAM treatments intended to produce benefits in these areas should be evaluable by using existing, standardized measures with strong scientific foundations.

Other potential outcomes of CAM treatments, however, are not as well defined or measurable. Feelings of general well-being, energy balance, harmony, or centeredness may be harder to measure in a reliable way, and perhaps hard to interpret outside the worldview or belief system of a specific CAM modality. Patients receiving an energy-based CAM therapy, for example, may very well understand questions about energy balance, and reliable and valid measures may be developed in the context of that therapy. The questions may not make as much sense to patients and the measures may not work as well, however, for patients receiving other treatment modalities. It will therefore be difficult to compare scores on such a measure across groups in comparative studies of the energy balance therapy and other CAM or non-CAM therapies. The same problem could hold in reverse, in that quantitative measures of pain intensity, for example, may not