summary.aov {stats}R Documentation

Summarize an Analysis of Variance Model


Summarize an analysis of variance model.


## S3 method for class 'aov'
summary(object, intercept = FALSE, split,
        expand.split = TRUE, = TRUE, ...)

## S3 method for class 'aovlist'
summary(object, ...)



An object of class "aov" or "aovlist".


logical: should intercept terms be included?


an optional named list, with names corresponding to terms in the model. Each component is itself a list with integer components giving contrasts whose contributions are to be summed.


logical: should the split apply also to interactions involving the factor?

logical: should terms with no degrees of freedom be included?


Arguments to be passed to or from other methods, for summary.aovlist including those for summary.aov.


An object of class c("summary.aov", "listof") or "summary.aovlist" respectively.

For fits with a single stratum the result will be a list of ANOVA tables, one for each response (even if there is only one response): the tables are of class "anova" inheriting from class "data.frame". They have columns "Df", "Sum Sq", "Mean Sq", as well as "F value" and "Pr(>F)" if there are non-zero residual degrees of freedom. There is a row for each term in the model, plus one for "Residuals" if there are any.

For multistratum fits the return value is a list of such summaries, one for each stratum.


The use of expand.split = TRUE is little tested: it is always possible to set it to FALSE and specify exactly all the splits required.

See Also

aov, summary, model.tables, TukeyHSD


## For a simple example see example(aov)

# Cochran and Cox (1957, p.164)
# 3x3 factorial with ordered factors, each is average of 12.
CC <- data.frame(
    y = c(449, 413, 326, 409, 358, 291, 341, 278, 312)/12,
    P = ordered(gl(3, 3)), N = ordered(gl(3, 1, 9))
CC.aov <- aov(y ~ N * P, data = CC , weights = rep(12, 9))

# Split both main effects into linear and quadratic parts.
summary(CC.aov, split = list(N = list(L = 1, Q = 2),
                             P = list(L = 1, Q = 2)))

# Split only the interaction
summary(CC.aov, split = list("N:P" = list(L.L = 1, Q = 2:4)))

# split on just one var
summary(CC.aov, split = list(P = list(lin = 1, quad = 2)))
summary(CC.aov, split = list(P = list(lin = 1, quad = 2)),
        expand.split = FALSE)

[Package stats version 4.4.0 Index]