Compound Symmetry Correlation Structure

DESCRIPTION:

This function is a constructor for the corCompSymm class, representing a compound symmetry structure corresponding to uniform correlation. Objects created using this constructor must be later initialized using the appropriate initialize method.

USAGE:

corCompSymm(value, form, fixed) 

OPTIONAL ARGUMENTS:

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 coefficient should be allowed to vary in the optimization, or kept fixed at its initial value. Defaults to FALSE, in which case the coefficient is allowed to vary.

VALUE:

an object of class corCompSymm, representing a compound symmetry correlation structure.

REFERENCES:

Milliken, G. A. and Johnson, D. E. (1992) "Analysis of Messy Data, Volume I: Designed Experiments", Van Nostrand Reinhold.

SEE ALSO:

EXAMPLES:

## covariate is observation order and grouping factor is Subject 
cs1 <- corCompSymm(0.5, form = ~ 1 | Subject)