formula for the fixed effects.

character; name of column in data.frame in which standard error (type="classical" or type="berkson") or miscalssification error (type="dclassical") is stored.

name of column in data.frame in which groups are stored. Rows of the design matrix with the same group level are assumed to pertain to the same obsevation of the covariate that is measured with error.

character; one of type="classical", type="berkson", type="dclassical" or type="dberkson" (see details)