CS | R Documentation |
Variance-covariance structure where the residuals have constant variance and correlation, possibly only within certain covariate levels. Can be stratified on a categorical variable.
CS(formula, var.cluster, var.time, heterogeneous = TRUE, add.time)
formula |
formula indicating on which variable to stratify the residual variance and correlation (left hand side) and variables influencing the residual variance and correlation (right hand side). |
var.cluster |
[character] cluster variable. |
var.time |
[character] time variable. |
heterogeneous |
[logical] when covariates are used for the correlation structure, should correlation parameters should be specific to each level of the covariate? |
add.time |
not used. |
A typical formula would be ~1
, indicating a variance constant over time and the same correlation between all pairs of times.
An object of class CS
that can be passed to the argument structure
of the lmm
function.
CS(~1, var.cluster = "id", var.time = "time") CS(gender~1, var.cluster = "id", var.time = "time") CS(list(~time,~1), var.cluster = "id", var.time = "time") CS(list(gender~time,gender~1), var.cluster = "id", var.time = "time")
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