ID {LMMstar}

identity Structure

Description

Variance-covariance structure where the residuals are independent and identically distributed. Can be stratified on a categorical variable.

Usage

ID(formula, var.cluster, var.time, add.time)

Arguments

formula

formula indicating on which variable to stratify the residual variance (left hand side).

var.cluster

[character] cluster variable.

var.time

[character] time variable.

add.time

not used.

Details

A typical formula would be ~1.

Value

An object of class IND that can be passed to the argument structure of the lmm function.

Examples

ID(NULL, var.cluster = "id", var.time = "time")
ID(~1, var.cluster = "id", var.time = "time")
ID(~gender, var.cluster = "id", var.time = "time")
ID(gender~1, var.cluster = "id", var.time = "time")