power.anova.test
Power Calculations for Balanced One-Way Analysis of Variance Tests
Description
Compute power of test or determine parameters to obtain target power.
Usage
power.anova.test(groups = NULL, n = NULL, between.var = NULL, within.var = NULL, sig.level = 0.05, power = NULL)
Arguments
groups | Number of groups |
n | Number of observations (per group) |
between.var | Between group variance |
within.var | Within group variance |
sig.level | Significance level (Type I error probability) |
power | Power of test (1 minus Type II error probability) |
Details
Exactly one of the parameters groups
, n
, between.var
, power
, within.var
, and sig.level
must be passed as NULL, and that parameter is determined from the others. Notice that sig.level
has non-NULL default so NULL must be explicitly passed if you want it computed.
Value
Object of class "power.htest"
, a list of the arguments (including the computed one) augmented with method
and note
elements.
Note
uniroot
is used to solve power equation for unknowns, so you may see errors from it, notably about inability to bracket the root when invalid arguments are given.
Author(s)
Claus Ekstrøm
See Also
Examples
power.anova.test(groups = 4, n = 5, between.var = 1, within.var = 3) # Power = 0.3535594 power.anova.test(groups = 4, between.var = 1, within.var = 3, power = .80) # n = 11.92613 ## Assume we have prior knowledge of the group means: groupmeans <- c(120, 130, 140, 150) power.anova.test(groups = length(groupmeans), between.var = var(groupmeans), within.var = 500, power = .90) # n = 15.18834
Copyright (©) 1999–2012 R Foundation for Statistical Computing.
Licensed under the GNU General Public License.