cohere {dfcrm} | R Documentation |
Coherence of two-stage CRM
Description
Returns a message on the coherence status of a two-stage CRM
design.
Usage
cohere(prior, target, x0, method = "bayes", model = "empiric",
intcpt = 3, scale = sqrt(1.34), detail = TRUE)
Arguments
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 model =``empiric'', this argument will be
ignored. |
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. |
Value
message |
A string character giving a message regarding the
coherence status of a two-stage CRM design. |
References
Cheung, Y. K. (2005). Coherence principles in dose-finding studies.
Biometrika 92:863-873.
See Also
crm
Examples
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)
[Package
dfcrm version 0.1-2
Index]