Coherence of two-stage CRM
Returns a message on the coherence status of a two-stage CRM design.
cohere(prior, target, x0, method = "bayes", model = "empiric",
intcpt = 3, scale = sqrt(1.34), detail = TRUE)prior |
A vector of initial guesses of toxicity probabilities associated the doses. |
target |
The target DLT rate. |
x0 |
The initial design containing a non-decreasing sequence of dose levels. The length of the initial design is the sample size. |
method |
A character string to specify the method for parameter estimation. The default method “bayes” estimates the model parameter by the posterior mean. Maximum likelihood estimation is specified by “mle”. |
model |
A character string to specify the working model used in the method. The default model is “empiric”. A one-parameter logistic model is specified by “logistic”. |
intcpt |
The intercept of the working logistic model. The
default is 3. If |
scale |
Standard deviation of the normal prior of the model parameter. Default is sqrt(1.34). |
detail |
If TRUE, details about incoherent escalations will be displayed. |
message |
A string character giving a message regarding the coherence status of a two-stage CRM design. |
Cheung, Y. K. (2005). Coherence principles in dose-finding studies. Biometrika 92:863-873.
Cheung, Y. K. (2011). Dose Finding by the Continual Reassessment Method. New York: Chapman & Hall/CRC Press.
prior <- c(0.05, 0.10, 0.20, 0.35, 0.50, 0.70) x0 <- c(rep(1,3), rep(2,3), rep(3,3), rep(4,3), rep(5,3), rep(6,9)) # The above design is coherent when target rate = 0.20 foo <- cohere(prior, target=0.2, x0) foo # The design is incoherent if a larger target DLT rate is used. foo2 <- cohere(prior, target=0.3, x0)
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