corCompSymm
class,
representing a compound symmetry structure corresponding to uniform
correlation. Objects created using this constructor must later be
initialized using the appropriate Initialize
method.corCompSymm(value, form, fixed)
~ t
, or ~ t |
g
, specifying a time covariate t
and, optionally, a
grouping factor g
. When a grouping factor is present in
form
, the correlation structure is assumed to apply only
to observations within the same grouping level; observations with
different grouping levels are assumed to be uncorrelated. Defaults to
~ 1
, which corresponds to using the order of the observations
in the data as a covariate, and no groups.FALSE
, in which case
the coefficients are allowed to vary.corCompSymm
, representing a compound
symmetry correlation structure.corClasses
,
Initialize.corStruct
,
summary.corStruct
## covariate is observation order and grouping factor is Subject
cs1 <- corCompSymm(0.5, form = ~ 1 | Subject)
# Pinheiro and Bates, pp. 222-225
fm1BW.lme <- lme(weight ~ Time * Diet, BodyWeight,
random = ~ Time)
# p. 223
fm2BW.lme <- update(fm1BW.lme, weights = varPower())
# p. 225
cs1CompSymm <- corCompSymm(value = 0.3, form = ~ 1 | Subject)
cs2CompSymm <- corCompSymm(value = 0.3, form = ~ age | Subject)
cs1CompSymm <- Initialize(cs1CompSymm, data = Orthodont)
corMatrix(cs1CompSymm)
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