getPriorParameters {bhmbasket}

getPriorParameters

Description

This function provides default prior parameters for the analysis methods that can be used in performAnalyses.

Usage

getPriorParameters(
  method_names,
  target_rates,
  n_worth = 1,
  tau_scale = 1,
  w_j = 0.5
)

Arguments

method_names

A vector of strings for the names of the methods to be used. Available methods: c("berry", "exnex", "exnex_adj", "pooled", "stratified")

target_rates

A vector of numerics in ⁠(0, 1)⁠ for the target rate of each cohort

n_worth

An integer for the number of subjects the variability of the prior should reflect response rate scale, Default: 1

tau_scale

A numeric for the scale parameter of the Half-normal distribution of \tau in the methods "berry", "exnex", and "exnex_adj", Default: 1

w_j

A numeric in ⁠(0, 1)⁠ for the weight of the Ex component in the methods "exnex" and "exnex_adj", Default: 0.5

Details

Regarding the default prior parameters for "berry", "exnex", and "exnex_adj":

• "berry": The mean of \mu is set to 0. Its variance is calculated as proposed in "Robust exchangeability designs for early phase clinical trials with multiple strata" (Neuenschwander et al. (2016)) with regard to n_worth. The scale parameter of \tau is set to tau_scale.

• "exnex": The weight of the Ex component is set to w_j. For the Ex component: The target rate that results in the greatest variance is determined. The mean of \mu is set to that target rate. The variance of \mu is calculated as proposed in "Robust exchangeability designs for early phase clinical trials with multiple strata" (Neuenschwander et al. (2016)) with regard to n_worth. The scale parameter of \tau is set to tau_scale. For the Nex components: The means of \mu_j are set to the respective target rates. The variances of \tau_j are calculated as proposed in "Robust exchangeability designs for early phase clinical trials with multiple strata" (Neuenschwander et al. (2016)) with regard to n_worth, see also getMuVar.

• "exnex_adj": The weight of the Ex component is set to w_j. For the Ex component: The target rate that results in the greatest variance is determined. The mean of \mu is set to 0. The variance of \mu is calculated as proposed in "Robust exchangeability designs for early phase clinical trials with multiple strata" (Neuenschwander et al. (2016)) with regard to n_worth, see also getMuVar. The scale parameter of \tau is set to tau_scale. For the Nex components: The means of \mu_j are set to the 0. The variances of \tau_j are calculated as proposed in "Robust exchangeability designs for early phase clinical trials with multiple strata" (Neuenschwander et al. (2016)) with regard to n_worth, see also getMuVar.

• "pooled": The target rate that results in the greatest variance is determined. The scale parameter \alpha is set to that target rate times n_worth. The scale parameter \beta is set to 1 - that target rate times n_worth.

• "stratified": The scale parameters \alpha_j are set to target_rates * n_worth. The scale parameters \beta_j are set to (1 - target_rates) * n_worth.

Value

A list with prior parameters of class prior_parameters_list

Author(s)

Stephan Wojciekowski

References

Berry, Scott M., et al. "Bayesian hierarchical modeling of patient subpopulations: efficient designs of phase II oncology clinical trials." Clinical Trials 10.5 (2013): 720-734.

Neuenschwander, Beat, et al. "Robust exchangeability designs for early phase clinical trials with multiple strata." Pharmaceutical statistics 15.2 (2016): 123-134.

See Also

performAnalyses setPriorParametersBerry setPriorParametersExNex setPriorParametersExNexAdj setPriorParametersPooled setPriorParametersStratified combinePriorParameters getMuVar

Examples

prior_parameters_list <- getPriorParameters(
  method_names = c("berry", "exnex", "exnex_adj", "pooled", "stratified"),
  target_rates = c(0.1, 0.2, 0.3))