getprior function

Samples from the specified prior distribution.

A sample of specified size is obtained from the prior distribution.

getprior(prior.alpha, n)

Arguments

• prior.alpha: A list of length 3 containing the distributional information for the prior. The first element is a number from 1-4 specifying the type of distribution. Options are

  1. Gamma(a, b), where a=shape, b=scale: mean=ab, variance=ab*b
  2. Uniform(a, b), where a=min, b=max
  3. Lognormal(a, b), where a=mean on the log scale, b=variance on the log scale
  4. Bivariate Lognormal(a, b), where a=mean vector on the log scale, b=Variance-covariance matrix on the log scale. This prior should be used only in conjunction with a two-parameter logistic model.

  The second and third elements of the list are the parameters a and b, respectively.

• n: The number of samples.

Details

A vector of size n is returned from the specified prior distribution.

Examples

prior.alpha <- list(1, 1, 1)
samples.alpha <- getprior(prior.alpha, 2000)
hist(samples.alpha)

References

Sweeting M., Mander A., Sabin T. bcrm: Bayesian Continual Reassessment Method Designs for Phase I Dose-Finding Trials. Journal of Statistical Software (2013) 54: 1--26. http://www.jstatsoft.org/article/view/v054i13

See Also

bcrm, find.x

Author(s)

Michael Sweeting mjs212@medschl.cam.ac.uk (University of Cambridge, UK), drawing on code originally developed by J. Jack Lee and Nan Chen, Department of Biostatistics, the University of Texas M. D. Anderson Cancer Center