Standard Errors for Contrasts among Model Terms - Generic Function
DESCRIPTION:
Returns the standard error of a specified contrast, or matrix of contrasts.

This function is generic (see Methods); method functions can be written to handle specific classes of data. Classes which already have methods for this function include: aov, aovlist

USAGE: 
se.contrast(x, contrast.obj, ...)
REQUIRED ARGUMENTS:
x:
a model object
contrast.obj:
A structure specifying the contrasts. See specific methods for details.
VALUE:
A matrix of standard errors corresponding to the contrasts.
SEE ALSO:
model.tables , se.contrast.aov .
EXAMPLES: 
se.contrast(gun.aov, list( Method == "M1", Method == "M2"), data = gun)