Dependability of Entrustable Professional Activity Portfolios in Otorhinolaryngology Residency: Nationwide Generalizability and Decision Study.

Background: Competency-based medical education increasingly uses digital workplace assessment platforms to collect longitudinal evidence of trainees' readiness for progressive responsibility. Entrustable professional activities (EPAs) translate competencies into observable clinical work, but individual workplace observations are context-dependent and may not support dependable progression decisions. Empirical guidance remains limited on how many observations, faculty raters, EPA titles, and workplace settings are needed for a dependable EPA portfolio. Objective: This study aimed to estimate EPA portfolio dependability for competency-based progression review using nationwide data from a digital workplace assessment platform in otorhinolaryngology-head and neck surgery residency training. Methods: We conducted a retrospective, nationwide cross-sectional generalizability and decision study using routinely collected EPA-based workplace assessment data from Taiwan's E-MyWay platform. The study included completed EPA observations from accredited otorhinolaryngology-head and neck surgery residency programs between August 2022 and May 2026. Faculty-assigned entrustment-supervision ratings were scored on a 5-level national EPA scale. The resident was the object of measurement, whereas faculty rater, EPA title, and workplace setting were measurement facets. The generalizability study partitioned rating variance into resident, facet, interaction, and residual components, which were subsequently used in decision-study projections of the generalizability coefficient, Phi coefficient, and absolute standard error of measurement under alternative portfolio configurations. Results: The analytic sample included 45,526 EPA observations involving 466 residents and 448 faculty raters across 35 training programs, 11 EPA titles, and 5 workplace settings. Residents had a median of 87 (IQR 47-124) observations and were assessed by a median of 9 (IQR 6-12) faculty raters across 11 (IQR 10-11) EPA titles and 5 (IQR 4-5) workplace settings. Single EPA observations were insufficient for resident-level summative interpretation. In the primary generalizability study, residual/encounter-level variance was the largest component, accounting for 40.1% of total variance; resident variance accounted for 26.9%, faculty rater variance accounted for 10.8%, and resident × faculty rater interaction for 10.4%. A study-defined well-distributed 10-observation portfolio achieved a generalizability coefficient of 0.77 but an absolute dependability coefficient (Phi) of 0.65. A 20-observation portfolio across 5 faculty raters, 5 EPA titles, and 3 workplace settings yielded a Phi of 0.76, and a 30-observation portfolio across 6 faculty raters, 6 EPA titles, and 4 workplace settings yielded a Phi of 0.80. Conclusions: Nationwide digital workplace assessment data showed that EPA portfolio dependability reflected both observation counts and sampling breadth across faculty raters, EPA titles, and workplace settings. These study-defined portfolio configurations may help clinical competency committees, residency programs, and specialty societies monitor portfolio completeness before progression deliberation. They should complement, rather than replace, narrative feedback, case complexity, performance trajectory, and committee judgment.