sim.icc: Simulate 2-level ICC(1) values with and without level-1...

In multilevel: Multilevel Functions

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 [e-mail]

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.

Bliese, P. D., Maltarich, M. A., Hendricks, J. L., Hofmann, D. A., & Adler, A. B. (2019). Improving the measurement of group-level constructs by optimizing between-group differentiation. Journal of Applied Psychology, 104, 293-302.

See Also

ICC1 sim.mlcor

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)
#items with no level-1 (within) correlation
ICC.SIM<-sim.icc(gsize=10,ngrp=100,icc1=.15,nitems=4) 
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 (within) correlation of .30
set.seed(15324)
ICC.SIM<-sim.icc(gsize=10,ngrp=100,icc1=.15,nitems=4, item.cor=.3) 
mult.icc(ICC.SIM[,2:5],ICC.SIM$GRP)
with(ICC.SIM,waba(VAR1,VAR2,GRP))$Cov.Theorem  #Examine CorrW 

## End(Not run)

multilevel documentation built on March 18, 2022, 5:47 p.m.