power.z.test: Power analysis for a one sample z-test

Description

A power analysis for a one sample z-test. The function requires $\alpha$, $\sigma$, the effect size, the type of test (one tailed or two-tailed), and either power (1 - $\beta$) or n (sample size). If n is provided, then power is calculated. Conversely, if one provides power, but not n, then n is calculated.

Usage

power.z.test(sigma = 1, n = NULL, power = NULL, alpha = 0.05, effect = NULL, 
test = c("two.tail", "one.tail"), strict = FALSE)

Arguments

sigma

The population standard deviation.

The sample size. Not required if power is specified.

power

The desired power. Not required if n is specified.

alpha

Probability of type I error.

effect

Effect size.

test

One of two choices: "two.tail" or "one.tail".

strict

Causes the function to use a strict interpretation of power in a two-sided test. If strict = TRUE then power for a two sided test will include the probability of rejection in the opposite tail of the true effect. If strict = FALSE (the default) power will be half the value of $\alpha$ if the true effect size is zero.

Value

sigma: The prescribed population variance.
n: The sample size.
power: The power.
alpha: The type I error probability.
test: The type of test prescribed.
effect: The effect size.

References

Bain, L. J., and M. Engelhardt (1992) Introduction to Probability and Mathematical Statistics. Duxbury press. Belmont, CA, USA.

Examples

Run this code

power.z.test(sigma=6,effect=5,power=.9,test="one.tail")