Monday, February 27, 2006

st: retrieving random effect variance equations after gllamm for calculating intraclass correlation coef

Dear Listers, After running a bivariate random effects model using gllamm such as the one below, how can I retrieve the stored variances in order to compute an intraclass correlation coeffiecient?

Thanks for your assistance Ben

gllamm testpos disgrp1 disgrp2, nocons i(study) nrf(2) eqs(disgrp1 disgrp2) /// > f(bin) l(logit) weight(wt) nip(15) from(a) ip(m) lf0(`k' `ll') adapt allc robust General model information ------------------------------------------------------------------------------

dependent variable: testpos family: binom link: logit denominator: 1 equation for fixed effects disgrp1 disgrp2 Random effects information for 2 level model ------------------------------------------------------------------------------

***level 2 (study) equation(s): (2 random effect(s)) diagonal element of cholesky decomp. of covariance matrix stu1_1 : disgrp1 diagonal element of cholesky decomp. of covariance matrix stu1_2 : disgrp2 off-diagonal elements stu1_2_1: _cons number of level 1 units = 1937 number of level 2 units = 30 ------------------------------------------------------------------------------ Non-adaptive log-likelihood: -779.03162 -779.0317 -779.0317 number of level 1 units = 1937 number of level 2 units = 30 Condition Number = 1.9473989 Robust standard errors

gllamm model Number of obs = 1937 LR chi2(0) = -0.01 Log likelihood = -779.03162 Prob > chi2 = .

------------------------------------------------------------------------------ testpos | Coef. Std. Err. z P>|z| [95% Conf. Interval] -------------+---------------------------------------------------------------- disgrp1 | -2.959496 .3009717 -9.83 0.000 -3.54939 -2.369603 disgrp2 | 1.06178 .2657384 4.00 0.000 .5409422 1.582618 ------------------------------------------------------------------------------ Variances and covariances of random effects ------------------------------------------------------------------------------

***level 2 (study) var(1): 1.3751185 (.4323597) cov(2,1): .54357384 (.44703036) cor(2,1): .3611499 var(2): 1.647411 (.58568729) ------------------------------------------------------------------------------

gllamm model Number of obs = 1937 LR chi2(0) = -0.01 Log likelihood = -779.03162 Prob > chi2 = .

------------------------------------------------------------------------------ testpos | Coef. Std. Err. z P>|z| [95% Conf. Interval] -------------+---------------------------------------------------------------- testpos | disgrp1 | -2.959496 .3009717 -9.83 0.000 -3.54939 -2.369603 disgrp2 | 1.06178 .2657384 4.00 0.000 .5409422 1.582618 -------------+---------------------------------------------------------------- stu1_1 | disgrp1 | 1.172654 .1843509 6.36 0.000 .8113334 1.533976 -------------+---------------------------------------------------------------- stu1_2 | disgrp2 | 1.196888 .152055 7.87 0.000 .8988655 1.49491 -------------+---------------------------------------------------------------- stu1_2_1 | _cons | .4635414 .384735 1.20 0.228 -.2905254 1.217608 ------------------------------------------------------------------------------

Ben Adarkwa Dwamena, MD

Assistant Professor of Radiology Division of Nuclear Medicine Department of Radiology University of Michigan Medical School 1500 E. Medical Center Drive B1 G505 University Hospital Ann Arbor, MI 48109-0028

bdwamena@umich.edu

http://sitemaker.umich.edu/metadiagnosis

Staff Physician D748 Nuclear Medicine Service (115), VA Ann Arbor Health Care System 2215 Fuller Road Ann Arbor, MI 48105 734-761-7886 Phone 734-761-5229 Fax

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