Oneway anova

To compare the means in three or more independent groups, oneway analysis of variance can be used. In this example, a dataset/dataframe called dat contains a categorical variable groupingVariable and a continuous variable dependentVariable.


The simplest analysis uses a function called ONEWAY:

ONEWAY dependentVariable BY groupingVariable.

However, to obtain an eta^2 effect size, a plot, or to test for equality of variances, the more powerful UNIVARIATE function must be used:

UNIANOVA dependentVariable BY groupingVariable


To only obtain the analysis of variance results, use the oneway function and only specify both variables:

oneway(dat$dependentVariable, dat$groupingVariable);

Additionally, descriptives, effect sizes, a plot, Levene’s test, and corrections for heterogeneous variances can be requested:

oneway(dat$dependentVariable, dat$groupingVariable,
       means = TRUE, levene = TRUE,
       corrections = TRUE, plot = TRUE);