Extracting actual elements from objects of class powPar {sse}

Extracting an actual n, theta, and xi

Description

Extracting the actual n, theta, or xi from an object of class powPar. This functions are needed within the 'power-function' for extracting always the actual element during evaluation.

Usage

n(x)
theta(x)
xi(x)

Arguments

x

An object of class powPar.

Details

During the evaluation process with powCalc every combination of n, theta, and xi is evaluated. The described functions extract the actual n, theta, or xi during the evaluation process. The evaluation process with powCalc changes the actual element to ensure that all combinations are evaluated.

When a objcect of class powPar is created, the first element of n, theta, or xi is also set to be the actual element. This allows to use this method also outside the evaluation with powCalc for testing the 'power function'.

Value

An integer value for n. A numeric value for theta and xi.

Note

Do not use the method pp inside the power-function e.g. like pp(x, "n"), because this would extract the whole vector of n and not just the actual element.

See Also

pp, for extracting all other elements provided by the user (exept n, theta, and xi.

Examples

## defining the range of n and theta to be evaluated
psi <- powPar(n = seq(from = 20, to = 60, by = 2),
              theta = seq(from = 0.5, to = 1.5, by = 0.1),
              muA = 0,
              muB = 1)

## extracting all elements of psi individually, starting with the first
n(psi)
theta(psi)
xi(psi)

## extracting all elements, not just the actual:
pp(psi, name = "n")
pp(psi, name = "theta")
pp(psi, name = "xi")

## an example of usage
powFun <- function(psi){
  power.t.test(n = n(psi),
               delta = pp(psi, "muA") - pp(psi, "muB"),
               sd = theta(psi)
               )$power
}

## testing the power-function
powFun(psi)