power.z.test {asbio}

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")