A Method for Obtaining an Unbiased Sample of Family Medicine Patients for Research Purposes

Introduction: Obtaining a representative patient sample for research purposes can be challenging. Classic probability sampling can be trusted, but these approaches are not always feasible; yet alternatives may introduce bias. We summarize relevant literature, the need for new approaches, and illustrate a practical hybrid approach that could consistently produce representative patient samples. Methods: Valid approaches shift sampling decisions from fallible interviewers to less fallible reproducible processes. In lieu of the interviewer's inclination to select particular patients, we used the day of the week, the appointment time, and the sequence of the patient's last name in the alphabet to select a sample for a consent process and a survey. Illustrative Use: Characteristics of the study sample (n = 225) were compared with the characteristics of the population (N = 1964) that had an office visit during the recruiting period. The data suggested that the study sample was highly representative of the population in this illustrative case. Discussion: A hybrid sampling approach, in the context of a brief consent process, and a nonthreatening interview produced a representative study sample, but formal evaluation via simulation is needed to validate the hybrid approach. Convenience samples of consecutive patients should be avoided to minimize bias. (J Am Board Fam Med 2011;24:583-588.)