R: Power Calculations for Two-Sample Test for Proportions with...

power_prop_test {MESS} | R Documentation

## Power Calculations for Two-Sample Test for Proportions with unequal sample size

### Description

Compute power of test, or determine parameters to obtain target power for equal and unequal sample sizes.

### Usage

    power_prop_test(n = NULL, p1 = NULL, p2 = NULL, sig.level = 0.05,
      power = NULL, ratio = 1, alternative = c("two.sided", "one.sided"),
      tol = .Machine$double.eps^0.25)

### Arguments

`n` | Number of observations (in group 1)
`p1` | Probability in one group
`p2` | Probability in other group
`sig.level` | Significance level (Type I error probability)
`power` | Power of test (1 minus Type II error probability)
`ratio` | The ratio n2/n1 between the larger group and the smaller group. Should be a value equal to or greater than 1 since n2 is the larger group. Defaults to 1 (equal group sizes)
`alternative` | String. Can be one- or two-sided test. Can be abbreviated.
`tol` | Numerical tolerance used in root finding, the default providing (at least) four significant digits

### Details

Exactly one of the parameters `n`, `delta`, `power`, `sd`, `sig.level`, `ratio` `sd.ratio` must be passed as NULL, and that parameter is determined from the others. Notice that the last two have non-NULL defaults so NULL must be explicitly passed if you want to compute them.

### Value

Object of class `power.htest`, a list of the arguments (including the computed one) augmented with `method` and `note` elements.

### Note

`uniroot` is used to solve power equation for unknowns, so you may see errors from it, notably about inability to bracket the root when invalid arguments are given.

### Author(s)

Claus Ekstrom claus@rprimer.dk

### See Also

`power.prop.test`, `power_t_test`, `power.t.test`

### Examples

    power_prop_test(n=NULL, p1=.65, p2=.85, power=.8, ratio=2)

[Package MESS version 0.5.6 Index]