focus on processes or outcomes or both. The outcomes of interest may be relatively restricted (e.g., safety but not effectiveness or costs) or a wide range of outcomes may be examined. Evaluations of efficacy such as randomized clinical trials test interventions under strictly controlled conditions to minimize the impact of "extraneous" variables, whereas evaluations of effectiveness attempt to test interventions under ordinary conditions and to identify how such extraneous variables affect results (Brook and Lohr, 1985).

For purposes of this report, an evaluation criterion is a measure, indicator, standard, or similar basis for describing outcomes or making judgments. Examples of criteria in common use in evaluations include mortality, hospital length of stay, and patient satisfaction. The committee focused on the set of basic concerns about the quality, accessibility, and cost of health care that lie at the core of most health services research and technology assessments. Because a comprehensive presentation of specific criteria appropriate for the heterogeneity of telemedicine applications was beyond the committee's resources, this report sets forth criteria in the form of questions with examples of the kinds of measures or standards that would be applied to particular telemedicine applications.

Drawing from a widely cited 1990 IOM report, the committee agreed that quality of care is "the degree to which health care services for individuals and populations increase the likelihood of desired health outcomes and are consistent with current professional knowledge" (IOM 1990c, p. 21). Consistent with the concepts set forth in a 1993 report (IOM, 1993a), the committee defined access as the timely receipt of appropriate health care. Costs measure the value of resources expended for an activity or objective. They are generally measured in dollars but are sometimes expressed in other units (e.g., travel time, days lost from work, treatment delays) without monetary conversion. These concepts and related evaluation topics (e.g., cost-effectiveness) are discussed further in later chapters of this report.

Although many telemedicine evaluations will focus on individual patient care, the growth of managed care and the debate over allocating resources for health care will direct more evaluations toward populations, including but not limited to those enrolled in managed care plans. Analyses may compare the costs, benefits, and risks of alternative services for an entire population or may concentrate on