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The stopping boundaries based on Lee and Liu's criterion.
stopbound_pred(theta, type, nmax, alpha_e, beta_e, p_s, theta_t)
the cutoff probability: typically, \(\theta = [0.95, 0.99]\) for superiority, \(\theta = [0.01, 0.05]\) for futility.
type of boundaries: "superiority" or "futility".
the maximum number of patients treated by the experimental drug.
the hyperparameter (shape1) of the Beta prior for the experimental drug.
the hyperparameter (shape2) of the Beta prior for the experimental drug.
the the response rate for the standard drug.
the prespecified target probability; tipically, \(\theta_T = [0.85, 0.95]\).
the boundaries set: \(U_n\) or \(L_n\)
Lee, J. J., Liu, D. D. (2008). A predictive probability design for phase II cancer clinical trials. Clinical Trials 5: 93-106.
Yin, G. (2012). Clinical Trial Design: Bayesian and Frequentist Adaptive Methods. New York: Wiley.
# NOT RUN { stopbound_pred(0.05, "futility", 40, 0.6, 1.4, 0.3, 0.85) stopbound_pred(0.05, "futility", 30, 0.4, 1.6, 0.2, 0.85) stopbound_pred(0.95, "superiority", 40, 0.6, 1.4, 0.3, 0.85) # }
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