power.z.test {asbio} R Documentation

## 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.

Ken Aho

### References

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

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