| corCompSymm {nlme} | R Documentation |
This function is a constructor for the 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)
value |
the correlation between any two correlated observations. Defaults to 0. |
form |
a one sided formula of the form ~ 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. |
fixed |
an optional logical value indicating whether the
coefficients should be allowed to vary in the optimization, or kept
fixed at their initial value. Defaults to FALSE, in which case
the coefficients are allowed to vary. |
an object of class corCompSymm, representing a compound
symmetry correlation structure.
Jose Pinheiro Jose.Pinheiro@pharma.novartis.com and Douglas Bates bates@stat.wisc.edu
Milliken, G. A. and Johnson, D. E. (1992) "Analysis of Messy Data, Volume I: Designed Experiments", Van Nostrand Reinhold.
## covariate is observation order and grouping factor is Subject cs1 <- corCompSymm(0.5, form = ~ 1 | Subject)