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

In asbio: A Collection of Statistical Tools for Biologists

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 the required 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.
n	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

Returns a list

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.

Author(s)

Ken Aho

References

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

See Also

pnorm

Examples

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

asbio documentation built on May 29, 2024, 5:57 a.m.