twoarmDesign {curtailment}

Find two-arm trial designs that use stochastic curtailment

Description

This function finds admissible design realisations for two-arm binary outcome trials, using stochastic curtailment. The output can be used as the sole argument in the function 'drawDiagram', which will return the stopping boundaries for the admissible design of your choice. Monitoring frequency can set in terms of block size.

Usage

twoarmDesign(
  nmin.arm,
  nmax.arm,
  block.size,
  minstop = NULL,
  pc,
  pt,
  alpha,
  power,
  maxthetaF = NULL,
  minthetaE = 0.7,
  bounds = "ahern",
  fixed.r = NULL,
  max.combns = 1e+06,
  rm.dominated.designs = TRUE,
  exact.thetaF = NULL,
  exact.thetaE = NULL,
  fast.method = FALSE
)

Arguments

nmin.arm

Smallest maximum sample size per arm. Should be a multiple of block size.

nmax.arm

Largest maximum sample size per arm. Should be a multiple of block size.

block.size

Block size.

minstop

Minimum permitted sample size at the first interim analysis.

pc

Anticipated response rate on the control arm.

pt

Anticipated response rate on the treatment arm.

alpha

Significance level

power

Required power (1-beta).

maxthetaF

Maximum value of lower CP threshold theta_F_max.

minthetaE

Minimum value of upper threshold theta_E_min.

bounds

choose what final rejection boundaries should be searched over: Those of A'Hern ("ahern"), Wald ("wald") or no constraints (NA). Defaults to "wald".

fixed.r

Choose what final rejection boundaries should be searched over. Useful for reproducing a particular design realisation. Defaults to NULL.

max.combns

Provide a maximum number of ordered pairs (theta_F, theta_E). Defaults to 1e6.

rm.dominated.designs

Logical. If TRUE, dominated designs will be removed from final output. Defaults to TRUE.

exact.thetaF

Provide an exact value for lower threshold theta_F. Useful for reproducing a particular design realisation. Defaults to NULL.

exact.thetaE

Provide an exact value for upper threshold theta_E. Useful for reproducing a particular design realisation. Defaults to NULL.

fast.method

Logical. If FALSE, design search is conducted over all combinations of (theta_F, theta_E). If TRUE, a much faster, though less thorough, design search is undertaken. Defaults to FALSE.

Value

Output is a list of two dataframes. The first, $input, is a one-row data frame that contains all the arguments used in the call. The second, $all.des, contains the operating characteristics of all admissible designs found.

Author(s)

Martin Law, [e-mail]

Examples

des <- twoarmDesign(nmin.arm=20,
nmax.arm=24,
block.size=8,
pc=0.1,
pt=0.4,
alpha=0.1,
power=0.8,
maxthetaF=0.4,
minthetaE=0.7,
max.combns=1e4)