ProfileLikelihood (version 1.1)

profilelike.lme: Profile Likelihood for Linear Mixed-Effects Models

Description

This function provides values for a profile likelihood and a normalized profile likelihood for a parameter of interest in a linear mixed-effects model.

Usage

profilelike.lme(formula, data, subject, random, correlation = NULL, 
	profile.theta, method = "ML", lo.theta, hi.theta, length = 300, 
	round = 2, subset = NULL, weights = NULL, ...)

Arguments

formula

see corresponding documentation in lme.

data

a data frame. See corresponding documentation in lme.

subject

see corresponding documentation in lme.

random

see corresponding documentation in lme.

correlation

see corresponding documentation in lme.

profile.theta

a parameter of interest, theta; must be a numeric variable.

method

see corresponding documentation in lme.

lo.theta

lower bound for a parameter of interest to obtain values for a profile likelihood.

hi.theta

upper bound for a parameter of interest to obtain values for a profile likelihood.

length

length of numerical grid values for a parameter of interest to obtain values for a profile likelihood.

round

the number of decimal places for round function to automatically define lower and upper bounds of numerical grid for a parameter of interest. If an automatically defined parameter range is not appropriate, increase the number or specify lo.theta and hi.theta.

subset

should not be provided.

weights

should not be provided.

…

further arguments passed to or from other methods.

Value

theta

numerical grid values for a parameter of interest in a specified range (between lower and upper bounds).

profile.lik

numerical values for a profile likelihood corresponding to theta in a specified range (between lower and upper bounds).

profile.lik.norm

numerical values for a normalized profile likelihood ranging from 0 to 1.

Warning

Arguments weights and subset in the lme function are not comparable.

Missing values should be removed.

Details

This function provides values for a profile likelihood and a normalized profile likelihood for a parameter of interest in a linear mixed-effects model. Users must define a parameter of interest in a linear mixed-effects model. This function can be used for models comparable with the lme function. However, arguments weights and subset should not be provided. A normalized profile likelihood is obtained by a profile likelihood being divided by the maximum value of the profile likelihood so that a normalized profile likelihood ranges from 0 to 1.

See Also

profilelike.plot, profilelike.summary, profilelike.lm, profilelike.glm, profilelike.polr, profilelike.gls, lme

Examples

# NOT RUN {
xx <- profilelike.lme(formula = yield ~ endpoint, random = ~ 1 | id, 
		correlation=corAR1(form = ~ 1 | id), data=Gasoline, subject="Sample", 
		profile.theta="vapor", method="ML", lo.theta=1, hi.theta=5, length=500, round=2)
profilelike.plot(theta=xx$theta, profile.lik.norm=xx$profile.lik.norm, round=4)
# }