designPilotSafeT {safestats}

Designs a Safe T-Test Based on Planned Samples nPlan

Description

Designs a safe experiment for a prespecified tolerable type I error based on planned sample size(s), which are fixed ahead of time. Outputs a list that includes the deltaS, i.e., the safe test defining parameter.

Usage

designPilotSafeT(
  nPlan = 50,
  alpha = 0.05,
  alternative = c("twoSided", "greater", "less"),
  h0 = 0,
  lowParam = 0.01,
  highParam = 1.2,
  tol = 0.01,
  inverseMethod = TRUE,
  logging = FALSE,
  paired = FALSE,
  maxIter = 10
)

Arguments

nPlan

the planned sample size(s).

alpha

numeric in (0, 1) that specifies the tolerable type I error control –independent of n– that the designed test has to adhere to. Note that it also defines the rejection rule e10 > 1/alpha.

alternative

a character string specifying the alternative hypothesis must be one of "twoSided" (default), "greater" or "less".

h0

a number indicating the hypothesised true value of the mean under the null. For the moment h0=0.

lowParam

numeric defining the smallest delta of the search space for the test-defining deltaS for scenario 3. Currently not yet in use.

highParam

numeric defining the largest delta of the search space for the test-defining deltaS for scenario 3. Currently not yet in use.

tol

a number that defines the stepsizes between the lowParam and highParam.

inverseMethod

logical, always TRUE for the moment.

logging

logical, if TRUE, then add invSToTThresh to output.

paired

logical, if TRUE then paired t-test.

maxIter

numeric > 0, the maximum number of iterations of adjustment to the candidate set from lowParam to highParam, if the minimum is not found.

Value

Returns an object of class 'safeDesign'. An object of class 'safeDesign' is a list containing at least the following components:

nPlan

the planned sample size(s).

parameter

the safe test defining parameter. Here deltaS.

esMin

the minimal clinically relevant standardised effect size provided by the user.

alpha

the tolerable type I error provided by the user.

beta

the tolerable type II error provided by the user.

alternative

any of "twoSided", "greater", "less" provided by the user.

testType

any of "oneSample", "paired", "twoSample" provided by the user.

paired

logical, TRUE if "paired", FALSE otherwise.

h0

the specified hypothesised value of the mean or mean difference depending on whether it was a one-sample or a two-sample test.

ratio

default is 1. Different from 1, whenever testType equals "twoSample", then it defines ratio between the planned randomisation of condition 2 over condition 1.

lowN

the smallest n of the search space for n provided by the user.

highN

the largest n of the search space for n provided by the user.

lowParam

the smallest delta of the search space for delta provided by the user.

highParam

the largest delta of the search space for delta provided by the user.

tol

the step size between lowParam and highParam provided by the user.

pilot

FALSE (default) specified by the user to indicate that the design is not a pilot study.

call

the expression with which this function is called.

Examples

designPilotSafeT(nPlan=30)