help quickicc
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Title

    quickicc --  Intraclass correlation and standard error calculation after
                   XTMIXED

Syntax
        quickicc

Description

    quickicc calcuates the intraclass correlation (ICC) after fitting a
    two-level xtmixed model where the intercept is the only random effect.
    In addition to calculating the ICC, this program also calculates the
    standard error of the maximum likelihood large sample ICC (see
    reference).

Examples

    First, fit an xtmixed model

    . use iccexample.dta, clear

    . xtmixed machach || l2id:

    Then, type quickicc

    . quickicc

    You can also find ICCs after models with several fixed effects

    . xtmixed machach f b h || l2id:

    . quickicc

Saved results

    quickicc saves the following in r():

    Scalars        
      r(l1vc)             the level 1 variance component
      r(l2vc)             the level 2 variance component
      r(tv)               the total variance
      r(N)                the number of observations from the xtmixed command
      r(m)                the number of groups from the xtmixed command
      r(icc)              the intraclass correlation
      r(se)               the standard error of the intraclass correlation

    Macros         
      r(model)            the previous xtmixed command

References

    Donner, A. & J. J. Koval.  1980.  The Large Sample Variance of an
        Intraclass Correlation.  Biometrika. 67:3. 719-722.