ppseq (version 0.2.5)

calc_next: Calculate response probability for the next patient

Description

This function is meant to be used in the context of a clinical trial with a binary endpoint. For the two-sample case, the total number of events in the standard-of-care arm is y0 and the total number of events in the experimental arm is y1. The function samples from the posterior beta distribution based on the data and the prior beta hyperparameters, and returns the empiric mean and bootstrap confidence interval for the next patient. The empiric mean represents the probability of the binary outcome occurring in the next patient. The one-sample case is also available.

Usage

calc_next(y, n, prior = c(0.5, 0.5), S = 5000, interval = 0.95)

Value

Returns a tibble with the group indicator (for the two-sample case only), the empiric mean, the bootstrap confidence interval, and the specified width of the confidence interval.

Arguments

y

number of events observed so far. Vector of length two c(y0, y1) for the two-sample case; integer y for the one-sample case.

n

sample size observed so far. Vector of length two c(n0, n1) for the two-sample case; integer n for the one-sample case.

prior

vector of length two containing hyperparameters of the prior beta distribution. c(0.5, 0.5) is default, for the Beta(0.5, 0.5) distribution.

S

number of samples, default is 5000

interval

a value between 0 and 1 indicating the width of the desired interval, default is 0.95

Examples

set.seed(123)

# One-sample case
calc_next(
  y = 27, 
  n = 100,
  S = 100
  )

# Two-sample case
calc_next(
  y = c(14, 23), 
  n = c(100, 100),
  S = 100
  )