powerAnalysis (version 0.2.1)

power.t: Power calculations for t-test

Description

Power calculations for t-test

Usage

power.t(es = NULL, n = NULL, power = NULL, sig.level = NULL, ratio = 1, type = c("two", "paired", "one", "unequal"), alternative = c("two.sided", "left", "right"))

Arguments

es

effect size.

n

total number of observations/pairs

power

power of study

sig.level

significance level

ratio

the ratio of sample size 1 to sample size 2. Only will be used when 'type' is "unequal".

type

type of t test, must be one of "one","two" (default), "paired", or "unequal". "one" means one sample t test, which test whether the population mean is equal to a specified value. "two"/"unequal" means two sample (equal size/unequal size) t test, which is used to ascertain how likely an observed mean difference between two groups would be to occur by chance alone. "paired" means paired t-test (also called the correlated t-test and the t-test for dependent means), which is used to ascertain how likely the difference between two means that contain the same (or matched) observations is to occur by chance alone.

alternative

One- or two-sided test, must be one of "two.sided" (default), "left", "right"

See Also

ES.t.one

ES.t.two

ES.t.paired

Examples

## one sample two sided test, calculate power
power.t(es=0.2,n=60,sig.level=0.10,type="one",alternative="two.sided")

## one sample one sided (left tail) test, calculate power
power.t(es=0.2,n=60,sig.level=0.10,type="one",alternative="left")

## one sample one sided (right tail) test, calculate power
power.t(es=0.2,n=60,sig.level=0.10,type="one",alternative="right")

## one sample two sided test, calculate sampe size
power.t(es=0.2,power=0.8,sig.level=0.05,type="one",alternative="two.sided")

## one sample two sided test, calculate effect size
power.t(n=200,power=0.8,sig.level=0.05,type="one",alternative="two.sided")

## one sample two sided test, calculate sig.level
power.t(es=0.2,n=200,power=0.8,type="one",alternative="two.sided")

## paired sample two sided test, calculate power
power.t(es=0.559,n=40,sig.level=0.05,type="paired",alternative="two.sided")

## paired sample two sided test, calculate sample size
power.t(es=0.15,power=0.8,sig.level=0.05,type="paired",alternative="two.sided")

## paired sample two sided test, calculate effect size
power.t(n=200,power=0.8,sig.level=0.05,type="paired",alternative="two.sided")

## two sample two sided test, calculate power
power.t(es=0.15,n=300,sig.level=0.05,type="two",alternative="two.sided")

## two sample two sided test, calculate sample size
power.t(es=0.15,power=0.8,sig.level=0.05,type="two",alternative="two.sided")

## two sample two sided test, calculate effect size
power.t(n=300,power=0.8,sig.level=0.05,type="two",alternative="two.sided")

## two sample (unequal size), calculate sample size
power.t(es=0.15,power=0.8,sig.level=0.05,type="unequal",ratio=2,alternative="two.sided")

power.t(es=0.1,n=3000,sig.level=0.05,type="unequal",ratio=2,alternative="two.sided")