Linked Questions

21
votes
2answers
41k views

“Model failed to converge” warning in lmer()

With the following dataset, I wanted to see if the response (effect) changes with regard to sites, season, duration, and their interactions. Some online forums on statistics suggested me to go on with ...
8
votes
2answers
4k views

How to deal with quasi-complete separation in a logistic GLMM?

Update: Since I now know that my problem is called quasi-complete separation I updated the question to reflect this (thanks to Aaron). I have a dataset from an experiment in which 29 human ...
0
votes
3answers
3k views

Mixed-effect model in R using lme for data count data with two fixed effects and repeated measures

I have no idea how to analyze this dataset. I am asking if two genotypes, T and M, respond differently to a treatment, E2 (I also have a control, CON). All 36 animals were given both E2 and CON in a ...
13
votes
0answers
5k views

Specify correlation structure for different groups in mixed-effects model (lme4/nlme)

I am trying to account for spatial autocorrelation in a linear mixed-effects model in R with measurements repeated in time. BodyMass has been collected once per <...
1
vote
1answer
730 views

Unbalanced mixed-effect model for repeated measures

I have a large set of point count data from 15 different sites that I wish to compare using R studio. Each site was surveyed multiple times each month from 2006-2015, except for some sites which were ...
2
votes
1answer
329 views

How to include random slopes for two binary repeated-measures factors?

I have a question regarding including my main predictors in the fixed as well as random effects term in a mixed model. I am using R and will provide a sample data set, but I am generally happy for ...
4
votes
2answers
168 views

How many groups are needed to reliably estimate variance parameters of random effects in a GLMM?

I am looking at a panel data with binary outcomes in each year. The ultimate use of the model I build is for prediction. The cross-sections are quite tall (~100,000 non-cases and ~5,000-20,000 cases) ...
1
vote
1answer
238 views

Should random and fixed factors be fully crossed (glmer)?

I have results from an experiment where seeds from 3 source populations (fixed factor 'Source') were transplanted into 4 sites (fixed factor 'site') in 3 different years (factor with levels 2011,2012,...
1
vote
1answer
117 views

Repeated, Spatial & Temporally Nested Design Confirmation

I'm an ecology grad student struggling to confirm proper analysis for the following experimental design: I identified 3 spatial blocks, each containing the same 3 plant types (tree, grass, shrub). ...
3
votes
1answer
112 views

Add extra level to multilevel model that was not part of the sampling process

Consider a population of students, clustered within schools. We are interested on explaining results of a math test at the student level. Assume we use a multistage sampling process in order to ...
4
votes
1answer
47 views

Mixed effects model for experimental setup

I conducted an experiment with a system that allows to perform a task on a test-object using several methods. The quality of how the task was performed is measured by an error. I measured the errors ...