Hall Christian Ich habe Dir hier den Output desselben Models mir den selben Daten mit R und mit Stata gerechnet angeh??ngt. Wie Du siehst sind die Unterschiede nicht unbetr??chtlich. Da Du bestimmt schon ??hnliche Erfahrungen gemacht hast, wollte ich Dich fragen, ob diese Unterschiede im Rahmen dessen sind, wie man sie zwischen zwei verschiedenen packages erwarten kann, oder nicht. F??r eine kurze Antwort w??re ich Dir sehr dankbar. Liebe Gr??sse Christian R output: GEE: GENERALIZED LINEAR MODELS FOR DEPENDENT DATA gee S-function, version 4.13 modified 98/01/27 (1998) Model: Link: Logit Variance to Mean Relation: Binomial Correlation Structure: Exchangeable Call: gee(formula = y ~ Var1 * Var2 + Var3, id = Var4, data = mydata, family = binomial, corstr = "exchangeable", scale.fix = TRUE) Summary of Residuals: Min 1Q Median 3Q Max -0.16457139 -0.10916961 -0.05774320 -0.01334249 0.98519918 Coefficients: Estimate Naive S.E. Naive z Robust S.E. Robust z (Intercept) -2.02946378 0.6152142 -3.29879234 0.6276423 -3.23347186 Var1med -0.06978758 0.8108207 -0.08607031 0.8280726 -0.08427713 Var1hi 0.08988940 0.9738316 0.09230487 0.9851523 0.09124417 Var2yes -2.16869738 1.2386945 -1.75079278 1.4269696 -1.51979227 Var3yes -0.10520805 0.5724176 -0.18379597 0.6881670 -0.15288157 Var1med:Var2yes 1.58088457 1.3503015 1.17076411 1.3682419 1.15541309 Var1hi:Var2yes 2.48367129 1.4694804 1.69016976 1.4707481 1.68871291 Estimated Scale Parameter: 1 Stata Output: xi: xtgee y i.Var1*i.Var2 Var3, family(binomial) link(logit) i(Var4) GEE population-averaged model Number of obs = 309 Group variable: Var4 Number of groups = 215 Link: logit Obs per group: min = 1 Family: binomial avg = 1.4 Correlation: exchangeable max = 8 Wald chi2(6) = 7.68 Scale parameter: 1 Prob > chi2 = 0.2628 ------------------------------------------------------------------------------ y | Coef. Std. Err. z P>|z| [95% Conf. Interval] -------------+---------------------------------------------------------------- _cons | -1.938584 .8662878 -2.24 0.025 -3.636477 -.2406913 _IVar1_2 | -.0610133 .8087995 -0.08 0.940 -1.646231 1.524205 _IVar1_3 | .0944082 .9720986 0.10 0.923 -1.81087 1.999686 _IVar2_2 | -2.178428 1.240422 -1.76 0.079 -4.60961 .2527538 Var3 | -.0977918 .5719084 -0.17 0.864 -1.218712 1.023128 _IVarXVa~2_2 | 1.575095 1.351553 1.17 0.244 -1.073901 4.22409 _IVarXVa~3_2 | 2.483814 1.470152 1.69 0.091 -.3976316 5.36526 ------------------------------------------------------------------------------ Christian -- Christian Bieli, project assistant Institute of Social and Preventive Medicine University of Basel, Switzerland Steinengraben 49 CH-4051 Basel Tel.: +41 61 270 22 12 Fax: +41 61 270 22 25 christian.bieli at unibas.ch www.unibas.ch/ispmbs