help iccvar-------------------------------------------------------------------------------

Title

iccvar-- intraclass correlation values and stadard errors for 2, 3, and 4 level models afterxtmixed.

Syntaxiccvar,[unb]-----------------------------------------------------------------------------

iccvarhas a special routine for 3-level models with unbalanced data. To enact this routine use theunboption.-----------------------------------------------------------------------------

Description

iccvaris a post-estimation command forxtmixed. After fitting a 2, 3, or 4 level model with a random intercept (random slopes are not supported),iccvarwill calculate the intraclass correlation (ICC) values and the associated standard errors based on the variance components and standard errors of the variance components estimated fromxtmixed.

Saved results

iccvarsaves the following inr():Scalars

r(p)the harmonic mean number of level 2 units per level 3 unitr(r)the harmonic mean number of level 3 units per level 4 unitr(tv)the total estimated variancer(lkvc)theklevel variance componentr(lkvc_v)theklevel variance component varianceMacros

r(model)thextmixedmodelMatrices

r(b)the matrix of ICCsr(V)the variance-covariance matrix of ICCs

AcknowledgmentsThe algorithms used in this program are based on Hedges, L. V., E. C. Hedberg and A. M. Kuyper. 2012. The Variance of Intraclass Correlations in Three- and Four-Level Models. Educational and Psychological Measurement. DOI: 10.1177/0013164412445193. Click for paper: link.

ContactThis program was written by Eric Hedberg, National Opinion Research Center at the University of Chicago. Any questions or comments can be directed to ech@uchicago.edu.