oneway.test {stats}  R Documentation 
Test for Equal Means in a OneWay Layout
Description
Test whether two or more samples from normal distributions have the same means. The variances are not necessarily assumed to be equal.
Usage
oneway.test(formula, data, subset, na.action, var.equal = FALSE)
Arguments
formula 
a formula of the form 
data 
an optional matrix or data frame (or similar: see

subset 
an optional vector specifying a subset of observations to be used. 
na.action 
a function which indicates what should happen when
the data contain 
var.equal 
a logical variable indicating whether to treat the
variances in the samples as equal. If 
Details
If the righthand side of the formula contains more than one term, their interaction is taken to form the grouping.
Value
A list with class "htest"
containing the following components:
statistic 
the value of the test statistic. 
parameter 
the degrees of freedom of the exact or approximate F distribution of the test statistic. 
p.value 
the pvalue of the test. 
method 
a character string indicating the test performed. 
data.name 
a character string giving the names of the data. 
References
B. L. Welch (1951). On the comparison of several mean values: an alternative approach. Biometrika, 38, 330–336. doi:10.2307/2332579.
See Also
The standard t test (t.test
) as the special case for two
samples;
the KruskalWallis test kruskal.test
for a nonparametric
test for equal location parameters in a oneway layout.
Examples
## Not assuming equal variances
oneway.test(extra ~ group, data = sleep)
## Assuming equal variances
oneway.test(extra ~ group, data = sleep, var.equal = TRUE)
## which gives the same result as
anova(lm(extra ~ group, data = sleep))