Case Deletion for mer/lmerMod objects

Description

This function is used to iteratively delete groups corresponding to the levels of a hierarchical linear model. It uses lmer() to fit the models for each deleted case (i.e. uses brute force). To investigate numerous levels of the model, the function will need to be called multiple times, specifying the group (level) of interest each time.

Usage

## Default S3 method:
case_delete(model, ...)

## S3 method for class 'mer'
case_delete(model, group = NULL, type = c("both", "fixef",
  "varcomp"), delete = NULL, ...)

## S3 method for class 'lmerMod'
case_delete(model, group = NULL, type = c("both", "fixef",
  "varcomp"), delete = NULL, ...)

Arguments

Value

a list with the following compontents:

fixef.original

the original fixed effects estimates

ranef.original

the original predicted random effects

vcov.original

the original variance-covariance matrix for the fixed effects

varcomp.original

the original estimated variance components

fixef.delete

a list of the fixed effects estimated after case deletion

ranef.delete

a list of the random effects predicted after case deletion

vcov.delete

a list of the variance-covariance matrices for the fixed effects obtained after case deletion

fitted.delete

a list of the fitted values obtained after case deletion

varcomp.delete

a list of the estimated variance components obtained after case deletion

Author(s)

Adam Loy loyad01@gmail.com

References

Christensen, R., Pearson, L.M., and Johnson, W. (1992) Case-Deletion Diagnostics for Mixed Models, Technometrics, 34, 38 – 45.

Schabenberger, O. (2004) Mixed Model Influence Diagnostics, in Proceedings of the Twenty-Ninth SAS Users Group International Conference, SAS Users Group International.

Examples

library(lme4)
data(sleepstudy, package = 'lme4')
fm <- lmer(Reaction ~ Days + (Days|Subject), sleepstudy)

# Deleting every Subject
fmDel <- case_delete(model = fm, group = "Subject", type = "both")

# Deleting only subject 308
del308 <- case_delete(model = fm, group = "Subject", type = "both", delete = 308)

# Deleting a subset of subjects
delSubset <- case_delete(model = fm, group = "Subject", type = "both", delete = 308:310)

Results

R version 3.3.1 (2016-06-21) -- "Bug in Your Hair"
Copyright (C) 2016 The R Foundation for Statistical Computing
Platform: x86_64-pc-linux-gnu (64-bit)

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> library(HLMdiag)

Attaching package: 'HLMdiag'

The following object is masked from 'package:stats':

    covratio

> png(filename="/home/ddbj/snapshot/RGM3/R_CC/result/HLMdiag/case_delete.mer.Rd_%03d_medium.png", width=480, height=480)
> ### Name: case_delete.default
> ### Title: Case Deletion for 'mer'/'lmerMod' objects
> ### Aliases: case_delete case_delete.default case_delete.lmerMod
> ###   case_delete.mer
> ### Keywords: models regression
> 
> ### ** Examples
> 
> library(lme4)
Loading required package: Matrix
> data(sleepstudy, package = 'lme4')
> fm <- lmer(Reaction ~ Days + (Days|Subject), sleepstudy)
> 
> # Deleting every Subject
> fmDel <- case_delete(model = fm, group = "Subject", type = "both")
> 
> # Deleting only subject 308
> del308 <- case_delete(model = fm, group = "Subject", type = "both", delete = 308)
> 
> # Deleting a subset of subjects
> delSubset <- case_delete(model = fm, group = "Subject", type = "both", delete = 308:310)
> 
> 
> 
> 
> 
> dev.off()
null device 
          1 
>