multilevel: sim.icc – R documentation

Become an expert in R — Interactive courses, Cheat Sheets, certificates and more!

sim.icc

Simulate 2-level ICC(1) values with and without level-1 correlation

Description

ICC(1) values play an important role influencing the form of relationships among variables in nested data. This simulation allows one to create data with known ICC(1) values. Multiple variables can be created both with and without level-1 correlation.

Usage

sim.icc(gsize, ngrp, icc1,nitems=1,item.cor=FALSE)

Arguments

`gsize`	The simulated group size.
`ngrp`	The simulated number of groups.
`icc1`	The simulated ICC(1) value.
`nitems`	The number of items (vectors) to simulate.
`item.cor`	An option to create level-1 correlation among items. Provided as a value between 0 and 1. If used, nitems must be larger than 1.

Value

`GRP`	The grouping designator.
`VAR1`	The simulated value. Multiple numbered columns if nitems>1

Author(s)

Paul Bliese paul.bliese@moore.sc.edu

References

Bliese, P. D. (2000). Within-group agreement, non-independence, and reliability: Implications for data aggregation and analysis. In K. J. Klein & S. W. Kozlowski (Eds.), Multilevel Theory, Research, and Methods in Organizations (pp. 349-381). San Francisco, CA: Jossey-Bass, Inc.

Examples

## Not run: 
set.seed(1535324)
ICC.SIM<-sim.icc(gsize=10,ngrp=100,icc1=.15)
ICC1(aov(VAR1~as.factor(GRP), ICC.SIM))

# 4 items with no level-1 correlation
set.seed(15324)
ICC.SIM<-sim.icc(gsize=10,ngrp=100,icc1=.15,nitems=4) #items with no level-1 correlation
mult.icc(ICC.SIM[,2:5],ICC.SIM$GRP)
with(ICC.SIM,waba(VAR1,VAR2,GRP))$Cov.Theorem  #Examine CorrW 

# 4 items with a level-1 correlation of .30
set.seed(15324)
ICC.SIM<-sim.icc(gsize=10,ngrp=100,icc1=.15,nitems=4, item.cor=.3) #.30 level-1 item correlations
mult.icc(ICC.SIM[,2:5],ICC.SIM$GRP)
with(ICC.SIM,waba(VAR1,VAR2,GRP))$Cov.Theorem  #Examine CorrW 

## End(Not run)

multilevel

Multilevel Functions

v2.6

GPL (>= 2)

Authors

Paul Bliese

Initial release

2016-07-26