It is often difficult to define the thing to be studied. Patients receiving homeopathy might also be accurately described as receiving a particular type, class, or school of homeopathic treatment; treatment from a particular type of provider or individual provider; and treatment with a particular material or combination of materials. Research could conceivably be done to establish the effectiveness of any of these things, from the most general to the most specific. The level of analysis that would be most informative for clinicians, individual patients, or health policy makers is not obvious. This problem is occasionally encountered in conventional medicine but less commonly than in CAM, as questions about effectiveness typically pertain to very precisely defined therapies rather than to whole disciplines or schools of thought (e.g., medicine, surgery, or radiation therapy). As a matter of convenience, one may speak of a study comparing surgical and medical treatments for low back pain, but a study would typically define the treatments in each domain quite specifically and not presume to be evaluating all possible treatments that might be offered under those broad labels. In CAM, however, there is a greater tendency to pose research questions about the effectiveness of whole modalities or schools of thought; for example, does chiropractic work for back or neck pain, and does acupuncture work for headache?
In CAM, treatments are individualized for each patient, and treatments may be individualized for each patient at each treatment (Park, 2002) One reason that research questions may be posed about whole CAM modalities at a time is that in some CAM modalities (e.g., traditional Chinese medicine) there is no such thing as a “standard” treatment or dose. Individualization of therapy to a unique combination of patient characteristics is a core concept of the modality. The only common characterstics to be studied across multiple patients and generalized from a study sample to a larger universe of patients are the modality and the general approach taken by the practitioner. Everything else can and will vary from patient to patient, at least in principle.
Some treatments are presumed to depend on the unique characteristics of the healer and on features of the healer-patient relationship. In some of the energy or touch therapies, for example, qi gong, the effectiveness of the treatment is presumed to be inherently bound up in a skill or an ability of the healer that may be viewed as a gift and therefore not easily measurable or generalizable (Krieger, 1998). This is not a completely foreign concept to research in conventional medicine; studies of surgical procedures typically take the skill or experience of the surgeon into account in some way; and studies of psychotherapy may take into account some measure of the skill, empathy level, or experience of the therapist. It is a complicating factor for research in any study in which the talents of service providers including conventional medicine vary and can be very problematic if the