ISSUE: Recent regulatory guidelines for collecting patient-focused data emphasize that samples must be representative of the target patient population. However, sample size estimation methods for qualitative studies to develop tools for patient-centered research have been questioned. The need to identify appropriate sample sizes is highlighted within ISPOR PRO Good Research Practices yet few practical guidelines are available. Recommendations from various researchers are inconsistent.
OVERVIEW: This panel discusses the theoretical underpinnings and practical considerations for sample size selection in qualitative research studies and will debate different approaches for COA development and validation. Kathy Lasch will present qualitative approaches to sample size selection for COA development and preference studies. Helen Doll will address alternative methods, including recent advances in quantitative social science methods (e.g. Fugard and Potts, 2015) and mixed method approaches. Katy Benjamin will debate the PROs and CONs of these approaches. All panelists will highlight clinical and practical factors which may influence sample size estimation for qualitative studies including study type, condition prevalence, number and size of subgroups of interest (e.g., condition or relevant demographic subtypes), complexity of the research question, interview length, and resource constraints. The panelists will debate methods and broaden discourse to advance qualitative research methodology.
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 Patrick DL, Burke LB, Gwaltney CJ, et al. Content validity - Establishing and reporting the evidence in newly-developed PRO instruments for medical product evaluation: ISPOR PRO good research practices task force report: Part 2 – Assessing respondent understanding. Value Health 2011;14; 978-988.
 Fugard AJB, Potts, HWW (2015) Supporting thinking on sample sizes for thematic analyses: a quantitative tool. International Journal of Social Research Methodology. Vol. 18 (6)