Notwithstanding the concerns about validity, the evaluation of many therapies begins with studies that use this type of design. Although conclusions drawn from the findings of such research are tentative, some results may be particularly meaningful. For example, the inability to demonstrate any positive outcomes would be unexpected, and would suggest that the specific intervention administered in the survey is unlikely to be effective.

The information that can be obtained from surveys that collect "pre-post" data can be enhanced in several ways. Entry criteria should be carefully stipulated to identify a sample that is best suited to show the effects of the intervention. For example, an effect on fatigue would be more likely to be demonstrable if the symptom were moderate or greater in intensity. Fatigue of this intensity for a defined period would be a useful entry criterion in most studies.

The timing and duration of data collection also should be carefully considered to maximize the likelihood of capturing effects and illuminating the time course, if this is of interest. For example, a study of an intervention for fatigue following radiation therapy for early-stage breast carcinoma should consider the time course of the symptom in this setting. All patients undergoing radiation would become candidates for screening questions, the purpose of which are to identify those patients who develop fatigue appropriate for the study. These screening questions might be asked on a weekly basis. Patients who experience a criterion level of fatigue (e.g. fatigue severe enough to interfere with functioning during the past week) would be asked to complete a baseline assessment. In most cases, this would occur before the radiation is completed. After this point, assessments might be planned for intervals that would likely capture additional weeks on therapy and a period of a month or two after radiation is completed (e.g. weekly for two assessments, biweekly for two assessments, and monthly for another one or two assessments). This assessment protocol is likely to elucidate outcomes that occur as radiation-related fatigue first increases, and then decreases.