help quickicc-------------------------------------------------------------------------------

Title

quickicc-- Intraclass correlation and standard error calculation after XTMIXED

Syntaxquickicc

Description

quickicccalcuates 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).

ExamplesFirst, fit an xtmixed model

. use iccexample.dta, clear

. xtmixed machach || l2id:Then, type quickicc

. quickiccYou can also find ICCs after models with several fixed effects

. xtmixed machach f b h || l2id:

. quickicc

Saved results

quickiccsaves the following inr():Scalars

r(l1vc)the level 1 variance componentr(l2vc)the level 2 variance componentr(tv)the total variancer(N)the number of observations from the xtmixed commandr(m)the number of groups from the xtmixed commandr(icc)the intraclass correlationr(se)the standard error of the intraclass correlationMacros

r(model)the previous xtmixed command

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