Power {epiDisplay} R Documentation

## Power calculation for two sample means and proportions

### Description

Calculation of power given the results from a study

### Usage

power.for.2p(p1, p2, n1, n2, alpha = 0.05)
power.for.2means(mu1, mu2, n1, n2, sd1, sd2, alpha = 0.05)

### Arguments

 p1, p2 probabilities of the two samples n1, n2 sample sizes of the two samples alpha significance level mu1, mu2 means of the two samples sd1, sd2 standard deviations of the two samples

### Details

These two functions compute the power of a study from the given arguments

### Author(s)

Virasakdi Chongsuvivatwong <cvirasak@medicine.psu.ac.th>

'n.for.2means', 'n.for.2p'

### Examples

# Suppose, in the example found in 'help(n.for.2p)',
# given the two proportions are .8 and .6 and the sample size
# for each group is 60.

power.for.2p(p1=.8, p2=.6, n1=60, n2=60) # 59 percent

# If the means of a continuous outcome variable in the same
# two groups were 50 and 60 units and the standard deviations were 30
# and 35 units, then the power to detect a statistical significance
# would be

power.for.2means(mu1=50, mu2=60, sd1=30, sd2=35, n1=60, n2=60)
# 39 percent. Note the graphic display

[Package epiDisplay version 3.5.0.1 Index]