power.z.test: Power calculations for two sample z tests

In felix-hof/biostatUZH: Misc Tools of the Department of Biostatistics, EBPI, University of Zurich

Power calculations for two sample z tests

Description

Power calculations for two sample z tests

Usage

power.z.test(
  n = NULL,
  delta = NULL,
  sd = 1,
  sig.level = 0.05,
  power = NULL,
  type = c("two.sample", "one.sample"),
  alternative = c("two.sided", "one.sided")
)

Arguments

n	Number of observations (per group)
delta	True difference in means
sd	Standard deviation
sig.level	Significance level (Type I error probability)
power	Power of test (1 minus Type II error probability)
type	String specifying the type of t test. Can be abbreviated.
alternative	One- or two-sided test. Can be abbreviated.

Details

Exactly one of the parameters n, delta, power, sd, and sig.level must be passed as NULL, and that parameter is determined from the others. Notice that the last two have non-NULL defaults, so NULL must be explicitly passed if you want to compute them.

Value

Object of class "power.htest", a list of the arguments (including the computed one) augmented with method and note elements.

Author(s)

Felix Hofmann

Examples

# Calculate sample size
delta = 0.25
sd = 0.4
sig.level = 0.01
power = 0.95
power.z.test(delta = delta, sd = sd, sig.level = sig.level, power = power)

# Calculate the effect size
n = 92
power.z.test(power = power, sd = sd, sig.level = sig.level, n = n)

# Calculate the standard deviation
power.z.test(power = power, delta = delta, sig.level = sig.level, n = n,
             sd = NULL)

# Calculate the type I error
power.z.test(power = power, delta = delta, sig.level = NULL, n = n,
             sd = sd)


# Calculate power
power.z.test(delta = delta, sd = sd, sig.level = sig.level, n = n)

felix-hof/biostatUZH documentation built on Sept. 27, 2024, 1:48 p.m.