All Questions
Tagged with lme4-nlme overdispersion
22 questions
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Statistical Inquiry. Overdispersion issue or abundance of 0s
Trying to go over some data and its half presence absence while the other half is count data. The model I've been working on lately is a mix of lmer and glmer.nb as that seems to be the approach for ...
- 1
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52
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Minor over-dispersion: reasonable to proceed with standard poisson GLMM?
I am using a Poisson GLMM with glmer() from lme4 package in R. My data is ecological count data, and the model has one random ...
- 11
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1
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417
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Dealing with singularity and overdispersion in GLMM?
I'm running a GLMM through the lme4 package in R to detect differences in time spent feeding (response) before and after birth (my 2 categories in the variable inf_cat).
I started with a Poisson GLMM, ...
- 67
4
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1
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706
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What is the best way to deal with over-dispersion in a poisson GLMM?
I am currently in the process of trying to complete a poisson GLMM analysis with two fixed (with an interaction) and two random effects using the glmer() function of the lme4 package. Using the ...
- 461
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211
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GLMER Overdispersion and Error messages
I have a data set which involves 30 binomial absence/presences totalled for a ratio out of 1, which is the total score of a test out of 30 marks.
The data requires fitting one of my predictor ...
- 77
5
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1
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652
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QQ plot doesn't look great - maybe quasipoisson with random effects?
I have several glmer()-models that look like this:
...
- 53
3
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58
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How to recalculate variance/covariance matrix adding a overdispersion term in glmm?
When models suffer from overdispersion, a solution is to calculate the dispersion parameter (using c_hat or dispersion_glmer in R for example). Then multiply the variance/covarianze matrix of ...
- 421
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410
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Validation of poisson GLMM corrected for overdispersion with OLRE
I am fitting a random effects model to some ecological count data (abundance). The aim is to analyse the effect of influence of chemical pest control on insect population. I run the analysis on ...
- 31
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Overdispersion in a binomial GLMER model
I'm having trouble accounting for overdispersion in a binomial GLMER (lme4 package) - I'd read through other posts on the topic but haven't found anything that solves my problem. I tried adding an ...
- 81
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Can including an observation level random effect (OLRE) create nested random factors in a GLMM?
I have data from an observational study on insect parasitism rates from 42 sites. Some sites were sampled only once and others were sampled multiple times across different years. For each sampling ...
- 31
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Is it appropriate to account for overdispersion in a glm by using a quasi-binomial distribution?
I have several sets of count data (as below) that are overdispersed. The overdispersion likely comes as a result of the number of zeros in the data which I understand means the paramater estimates in ...
- 273
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125
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Testing the assumptions of null models when using likelihood ratio tests to compare mixed-effect models
I have ran a Generalized mixed-effect model using the glmer function in the lme4 package. To appraise the significance of the model, I am using a likelihood ratio test. For example, if testing the '...
- 225
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1
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8k
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How to check overdispersion of binomial GLMMs, lme4 package
I have the following model
fit1 <- glmer(Res~FA+FB+FC+(1|fsite), family=binomial(), data=DATA)
the result of summary() ...
- 53
0
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1
answer
679
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Calculating QAICc and Averaging GLMM models with various overdispersion
I am having difficulty figuring out how to calculate a dispersion parameter to calculate QAICc for a GLMM with a binomial fit.
I have tested for overdispersion using this code:
...
- 11
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2k
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GLMM: relationship between AIC, R squared and overdispersion?
First of all, I am a beginner in statistics, and I have been reading some questions and comments here regarding this matter but I am still a bit lost.
My problem:
I am constructing GLMM's in order to ...
- 637
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1k
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Fitting binomial regression model in R - correct formula, significance testing, and over-dispersion
I'm using generalized linear models to test for the effect of various predictors on some binomial data. My response is a binomial vector of successes and non-successes.
I want to test whether my ...
- 1,118
2
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167
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How can I deal with overdispersed count data if I have a nested design?
I am trying determine whether pollen tube counts differ between nectar-robbed and un-robbed flowers. Pollen tube counts are nested within plant (multiple flowers of each type sampled from each plant) ...
- 805
5
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1
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4k
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Individual level random effect for over dispersion
In glms we can use a quassipoison fudge factor to account for over dispersion in our poisson models.
In glmms we can add an individual level random effect (e.g. id)...
- 1,625
3
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354
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Multilevel model specification for count data (with overdispersion) in R
I would like to specify a multilevel model including the following variables:
DV: count data, i.e. a score value between 0 and 13 (resulting from an additive index) for each individual
Individual ...
- 31
4
votes
1
answer
11k
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How to fix an overdispersion in a Poisson GLMM with glmer function in R?
I want to model counts as being dependent on two nominal variables, one continuous variable (all as fixed effects) with 3rd-order interactions and one grouping variable (as random effect). However, I ...
12
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2
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23k
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How to test for overdispersion in Poisson GLMM with lmer() in R?
I have the following model:
> model1<-lmer(aph.remain~sMFS1+sAG1+sSHDI1+sbare+season+crop
+(1|landscape),family=poisson)
...and this is the summary ...
- 711
33
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4
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18k
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How do I fit a multilevel model for over-dispersed poisson outcomes?
I want to fit a multilevel GLMM with a Poisson distribution (with over-dispersion) using R. At the moment I am using lme4 but I noticed that recently the ...
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