Читать книгу Medical Statistics - David Machin - Страница 101

Farndon et al. (2013) give the successful response rate to scalpel treatment in 94 patients with foot corns as 21%. From their data we have p = 20/94 = 0.21. Suppose a podiatrist treated four patients with corns with scalpel debridement. What is the probability that at most one patient responds to treatment? This implies that either 0 or 1 respond. We can use formula 4.1, with r = 0 to give 1 × 0.21⁰ × (1–0.21)⁴ = 0.3895 and with r = 1 to give 4 × 0.21¹ × (1–0.21)³ = 0.4142. Summing these two probabilities gives P = 0.3895 + 0.4142 = 0.8037.