unity {mreg}

The default value of 'modify' function in 'mreg'

Description

If the location term in a regression model does not depend on any previously observed values of the outcome in a longitudinal data set, then we obtain simplification in our estimation procedure when the outcomes can be missing. Using the default value of unity for the argument modify in the mreg function does this.

Usage

unity(x, y, mod.Z)

Arguments

x

is a vector of possible values the previous value of the response could take.

y

is an vector of the coefficients. Its length is specified in the mreg function by the argument modify.p.

mod.Z

vector of observed covariates that may interact with the unobserved preceding outcome corresponding to the observation. It is taken from the model.frame produced by the mod.formula argument in mreg.

Details

This function is the default value for the argument modify for mreg. It does nothing to the linear predictor term. For this function unity there are no such covariates. A default value for mod.formula is ~1.

Value

A vector of zeroes the same length is the argument x.