visit (version 2.2)

vtPriorPar: Get prior distribution parameters

Description

Get prior distribution parameters for partially parametric or partially parametric+ models

Usage

vtPriorPar(prior.y = NULL, tau = NULL, sdalpha = 10, sdrho = 10,
  vtheta = NULL)

Value

A VTPRIOR list with

• TAU:vector of \(\tau\)'s for each level

• ABCD:A matrix of 4 columns: \(a_q\), \(b_q\), \(a_\rho\), \({\sigma_\rho}\). Each row represents a dose level.

Arguments

prior.y

Historical data for generating prior parameters. It has the same structure as obs.y in vtPost.

tau

Vector of \(\tau\) values. See visit for details. Can not be NULL if prior.y is NULL.

sdalpha

\(\sigma_\alpha\). See visit for details.

sdrho

\(\sigma_\rho\).

vtheta

Additional variance term for eliciting prior parameters from prior.y

Details

The priors are specified as \(q^{(l)} \sim Beta(a_q^{(l)}, b_q^{(l)})\), and \(\log\rho^{(l)} \sim N(0, \sigma_\rho^2)\).

Examples

par.prior <- vtPriorPar(tau = c(0.2, 0.4, 0.6), sdalpha = 10);