# Samples from the specified prior distribution.

### Description

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

### Usage

1 | ```
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 Gamma(a,b), where a=shape, b=scale: mean=a*b, variance=a*b*b Uniform(a,b), where a=min, b=max Lognormal(a,b), where a=mean on the log scale, b=variance on the log scale 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.

### 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

### 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`

### Examples

1 2 3 |