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 α, σ, the effect size, the type of test (one tailed or two-tailed), and either power (1 - β) 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 α 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")