Apparently I have two questions tonight. I keep receiving an error on two sets of models I'm trying to compare using LRT via Anova command. I am confused why these models won't compare when my others are. I'm conducting a 3 level analysis, and as part of my moderator analysis I am adding a single fixed variable to the original fit, and then comparing the two models with anova. The original models were fit using REML, but for comparison purposes I have refit with ML. There are two sets of models where I get the following error: Error in anova.rma(rq1.fit2.ml, rq2.age.ml) : Observed outcomes and/or sampling variances/covariances not equal in the full and reduced model. Error in anova.rma(rq1.fit2.ml, rq2.dose.h.ml) : Observed outcomes and/or sampling variances/covariances not equal in the full and reduced model. Why might this be the case? And how can I fix it? Best (again), Jake Downs
[R-meta] Comparing Models Using Anova () Error
2 messages · Jake Downs, Wolfgang Viechtbauer
Dear Jake, As the error says, the datasets used to fit the two models are not identical. This is very likely a result of missing values in those moderators. Hence, the dataset used for fitting the model without the moderator is not the same as with. For a meaningful comparison, fit the model without the moderator selecting only those rows where the moderator variable is not missing (use something like subset=!is.na(...)) when fitting the model). Best, Wolfgang
-----Original Message----- From: R-sig-meta-analysis [mailto:r-sig-meta-analysis-bounces at r-project.org] On Behalf Of Jake Downs Sent: Wednesday, 24 March, 2021 2:08 To: r-sig-meta-analysis at r-project.org Subject: [R-meta] Comparing Models Using Anova () Error Apparently I have two questions tonight. I keep receiving an error on two sets of models I'm trying to compare using LRT via Anova command. I am confused why these models won't compare when my others are. I'm conducting a 3 level analysis, and as part of my moderator analysis I am adding a single fixed variable to the original fit, and then comparing the two models with anova. The original models were fit using REML, but for comparison purposes I have refit with ML. There are two sets of models where I get the following error: Error in anova.rma(rq1.fit2.ml, rq2.age.ml) : Observed outcomes and/or sampling variances/covariances not equal in the full and reduced model. Error in anova.rma(rq1.fit2.ml, rq2.dose.h.ml) : Observed outcomes and/or sampling variances/covariances not equal in the full and reduced model. Why might this be the case? And how can I fix it? Best (again), Jake Downs