Sample size of crew members changing health and morbidity before and after a cruise We took the entire crew members to fully participate in the voyage over 10 vessels under the study of 230 crew members Sample size for intervention research Applying formula: p1 (1-p1) + p2 (1-p2) n = Z 2 (α, β) ————————— (p1 - p2) 2 7 Substituting the data into the formula, we calculate n = 75.