weights_fujikawa {baskexact}  R Documentation 
Weights Based on Fujikawa et al.'s Design
Description
Weights Based on Fujikawa et al.'s Design
Usage
weights_fujikawa(design, ...)
## S4 method for signature 'OneStageBasket'
weights_fujikawa(
design,
n,
lambda,
epsilon = 1.25,
tau = 0.5,
logbase = 2,
prune = FALSE,
globalweight_fun = NULL,
globalweight_params = list(),
...
)
## S4 method for signature 'TwoStageBasket'
weights_fujikawa(design, n, n1, epsilon = 1.25, tau = 0, logbase = 2, ...)
Arguments
design 
An object of class 
... 
Further arguments. 
n 
The sample size per basket. 
lambda 
The posterior probability threshold. See details for more information. 
epsilon 
A tuning parameter that determines the amount of borrowing. See details for more information. 
tau 
A tuning parameter that determines how similar the baskets have to be that borrowing occurs. See details for more information. 
logbase 
A tuning parameter that determines which logarithm base is used to compute the JensenShannon divergence. See details for more information. 
prune 
Whether baskets with a number of responses below the
critical pooled value should be pruned before the final analysis.
If this is 
globalweight_fun 
Which function should be used to calculate the global weights. 
globalweight_params 
A list of tuning parameters specific to

n1 
The sample size per basket for the interim analysis in case of a twostage design. 
Details
weights_fujikawa
calculates the weights used for sharing
information between baskets based on the proposal by Fujikawa et al. (2020).
The weight for two baskets i and j is found as
(1  JSD(i, j))^\varepsilon
where JSD(i, j)
is the JensenShannon
divergence between the individual posterior distributions of the response
probabilities of basket i and j. Note that Fujikawa's weights also share the
prior information between the baskets.
A small value of epsilon results in stronger borrowing also across baskets with heterogenous results. If epsilon is large then information is only borrowed between baskets with similar results. If a weight is smaller than tau it is set to 0, which results in no borrowing.
If prune = TRUE
then the baskets with an observed number of baskets
smaller than the pooled critical value are not borrowed from. The
pooled critical value is the smallest integer c for which all null
hypotheses can be rejected if the number of responses is exactly c for
all baskets.
The function is generally not called by the user but passed to another
function such as toer
and pow
to specificy
how the weights are calculated.
Value
A matrix including the weights of all possible pairwise outcomes.
Methods (by class)

weights_fujikawa(OneStageBasket)
: Fujikawaweights for a singlestage basket design. 
weights_fujikawa(TwoStageBasket)
: Fujikawaweights for a twostage basket design.
References
Fujikawa, K., Teramukai, S., Yokota, I., & Daimon, T. (2020). A Bayesian basket trial design that borrows information across strata based on the similarity between the posterior distributions of the response probability. Biometrical Journal, 62(2), 330338.
Examples
design < setupOneStageBasket(k = 3, p0 = 0.2)
toer(design, n = 15, lambda = 0.99, weight_fun = weights_fujikawa)