summary.aov {stats} | R Documentation |
Summarize an analysis of variance model.
## S3 method for class 'aov'
summary(object, intercept = FALSE, split,
expand.split = TRUE, keep.zero.df = TRUE, ...)
## S3 method for class 'aovlist'
summary(object, ...)
object |
An object of class |
intercept |
logical: should intercept terms be included? |
split |
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. |
expand.split |
logical: should the split apply also to interactions involving the factor? |
keep.zero.df |
logical: should terms with no degrees of freedom be included? |
... |
Arguments to be passed to or from other methods,
for |
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.
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))
summary(CC.aov)
# 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)