Questions tagged [glmm]

Generalized Linear Mixed (effects) Models are typically used for modeling non-independent non-normal data (eg, longitudinal binary data).

GLMMs are a broad class of models: both linear mixed effects models and generalized linear models can be understood as special cases of GLMMs. GLMMs handle non-independence by including random effects. GLMMs are often contrasted with Generalized Estimating Equations, which may offer alternative approaches in many cases.

Related tags: multilevel-analysis, mixed-effect, random-effects-model, mixed-model, lmer, glmer, gllamm. Multilevel-analysis is an encompassing class of models. Mixed-effect and random-effects-model are used to describe a regression-like model in which the fixed effects of covariates are augmented with random effects, to be intergrated out in ML or REML estimation. Mixed-model is a linear model with a Gaussian response. lmer and glmer are R implementation in lme4 package of mixed models and GLMMs, respectively. gllamm is stata implementation of GLMMs.

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Interaction using generalized linear mixed model

I am conducting a GLMM. I currently have two independent variables (1, 2) and a dependent variable () - all factors (either 0 or 1). m <- glmer(y ~ x1+x2+x1:x2 + (1 | participant), data = mydata, family = binomial) I am mostly interested in the x1…
Sharon
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Should I take the arithmetic mean of variates which vary on smaller time scales in a linear regression?

I am consulting with another student with a stats background, but am pretty sure he his saying something that contradicts what I have been told about my data. I have a daily response variable measured on 16 individuals in a GLMM where the random…
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REML use in GLMM

I would like to make an enquiry regarding the use of ML or REML for GLMM. At the moment, I'm focusing on doing model selection to evaluate the effect of four fixed effects and one random effect on a response variable (continuous data) in a study of…
user20347
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GLMM indicates a negative trend, graph shows a positive trend

I'm analyzing my data in R using a GLMM, of the format: glmer(y~x1+x2+x3+x4+(1|site),data=df,family=poisson) This produces a negative trend for variable x3. On the other hand, the graph of this result produces a positive trend. According to the…
Pitto
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GLMM multilevel (hierarchical) model

I want to study the classroom and the school effect/result on the pupil's success (or not) at school. I also want to know the effect of the age, the gender (of the pupils) and if the pupils have or not repeated 1 year school on the pupil's success…
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Random effects are not normal

I'm doing a neg binomial glmm in glmmADMB. The random effects are not quite normally distributed (see attached images). How concerned about this do I need to be? If this is too much of a violation, are there other options for analyzing…
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Pitfalls in doing GLMM or interpreting GLMM results

I know this is a general question, but it would benefit CVers to learn about common pitfalls, things to consider and caveats on how to do rigorous GLMM modeling. Could those with experience on GLMMs share any insights they might have?
Moe
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wildly different parameter estimates in Generalized Linear Mixed Model in response to conceptually irrelevant (?) change

I’m analyzing some data per GLMM with a probit link function and I'm getting some weird inconsistencies between two GLMM specifications that, in my understanding, shouldn't be all that different. Let me give you some context about the experiment.…
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Multiple random effects in a generalized linear mixed model

I'm looking for an example of a data set that can be fitted using a GLMM with at least 3 separate random effects. I've taken a look at a few books on GLMM's including the one by McCulloch and Searle, but their examples always stop at 2 random…
viicii
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Comparing fixed effects of a binomial GLMM

I got stuck interpreting the result of a generalised linear mixed model (GLMM). Feedbacks on how to compare two coefficients within a categorical fixed effect would be really helpful! To be specific, the research question I ask is that are…
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Missing values in generalized linear mixed models (GLMMs)

I conducted a cognitive experiment where I coded several behavioral patterns. One pattern is the latency between the start of the experiment and the first behavioral response of the participant. I would like to estimate a probability model for this…
Tony
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Can I use GLMM?

I wonder if anyone would like to give me some guidance (I am a beginner in R). My data comes from a forest, where they performed a conservation fire. We measured the volume of trees before the fire (2007) and after (2013 and 2016) in eight plots. I…
Annie
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Alternative to GLMM for normalised ratio (Bounded: -1 to 1) response variable

My response variable is a metric calculated from the normalised ratio of two variables. Calculated as (a-b)/(a+b), resulting in a normalised ratio of continuous data bounded between -1 and +1 - my metric contains no values that are exactly -1 or 1,…
CM3
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GLMM multilevel hierarchical model with R

I hope I will get your precious help for my R problem. I want to study the classroom, the teacher and the school effect/result on the pupil's success (or not) at school. I also want to know the effect of the age, the gender and if the pupils have or…
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How do I specify a mixed effects model for a stepped-wedge cluster randomised trial?

I have been asked to asked to analyse a stepped-wedge cluster randomised trial that I did not design. Because the trial protocol has already been registered, I don't have much flexibility in the way the analysis needs to be performed. The trial…
Zoë
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