R: Power calculation for two proportions (same sample sizes)

pwr.2p.test {pwr} | R Documentation

## Power calculation for two proportions (same sample sizes)

### Description

Compute power of test, or determine parameters to obtain target power (similar to power.prop.test).

### Usage

    pwr.2p.test(h = NULL, n = NULL, sig.level = 0.05, power = NULL,
        alternative = c("two.sided","less","greater"))

### Arguments

`h` | Effect size
`n` | Number of observations (per sample)
`sig.level` | Significance level (Type I error probability)
`power` | Power of test (1 minus Type II error probability)
`alternative` | a character string specifying the alternative hypothesis, must be one of "two.sided" (default), "greater" or "less"

### Details

Exactly one of the parameters 'h','n', 'power' and 'sig.level' must be passed as NULL, and that parameter is determined from the others. Notice that the last one has non-NULL default so NULL must be explicitly passed if you want to compute it.

### 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)

Stephane Champely <champely@univ-lyon1.fr> but this is a mere copy of Peter Dalgaard work (power.t.test)

### References

Cohen, J. (1988). Statistical power analysis for the behavioral sciences (2nd ed.). Hillsdale,NJ: Lawrence Erlbaum.

### See Also

ES.h, pwr.2p2n.test, power.prop.test

### Examples

    ## Exercise 6.1 p. 198 from Cohen (1988)
    pwr.2p.test(h=0.3,n=80,sig.level=0.05,alternative="greater")

[Package pwr version 1.2-2 Index]