help iccvar
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Title

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

Syntax
        iccvar, [unb]

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  iccvar has a special routine for 3-level models with unbalanced data. To
  enact this routine use the unb option.

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Description

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

Saved results

    iccvar saves the following in r():

    Scalars        
      r(p)                the harmonic mean number of level 2 units per level
                            3 unit
      r(r)                the harmonic mean number of level 3 units per level
                            4 unit
      r(tv)               the total estimated variance
      r(lkvc)             the k level variance component
      r(lkvc_v)           the k level variance component variance

    Macros         
      r(model)            the xtmixed model

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

Acknowledgments

The 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.

Contact

    This 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.