All Questions
Tagged with ecology generalized-linear-model
33 questions
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21
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At what stage of the species distribution modelling to standardize variables and check for collinearity
I try to model the distribution (ecological niche) of a species using a generalized linear model (glm() in R) based on several climatic variables and then apply the ...
- 183
2
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96
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Dealing with Underdispersion in Poisson Regression (GLM) with count data as a response variable
Related to glm() in R, I am working with count data (number of mammal species on islands) and following statistical theory, I have fitted a ...
- 21
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37
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glmmTMB for non-regression ecological count data?
Study design: I am analyzing ecological count data for fish in a pre-existing database with observations of fish species abundances(zero_filled). Each species were recorded at a site twice a month of ...
- 63
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62
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Can I ignore high multicollinearity in a proportional binomial GLM from a fully factorial experimental design dataset?
I am running proportional binomial GLMs with 2 factors (Test Salinity and Region) but I am running into an issue with high multicollinearity. The reason for this is because this is a lab experiment ...
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103
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Need some advice in selection of GAM model - choosing family, etc
I am not a statistician (clearly) and am trying to wrangle environmental data. My data looks like (note data is on time scale - 1 = Day 1, 650 = Day 30:
I am developing a GAM model which predicts the ...
- 11
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1
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441
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Binomial GLM for attracting large mammal from presence/absence data
This is my first post here so I apologise if it is formatted incorrectly or missing key info.
I need a little bit of help/direction with interpreting R results for a project. Basic premise of project ...
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0
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104
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How to compare trend of two different datasets?
I have two different datasets (ID 1 and 2) which show the number of animals per hectare for each year. I need to know if the trend for the first periode is different then the trend for the second ...
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1
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1
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168
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When does a group specific dispersion parameter for the negative binomial distribution make sense?
If you have overdispersed observed abundance of multiple species including zero inflation the negative binomial distribution seems to be a reasonable choice. But if some species occur much more ...
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1
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2k
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Which link function could be used for a glm where the response is per cent (0 - 100%)?
I am thinking about building a model (glm) where the response variable (y) is the cover (in per cent) of a plant species in a defined area, dependant of environmental variables.
However, I don't think ...
- 195
4
votes
1
answer
405
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Best practice MLR vs GLM(M)
I am modelling timeseries of organism traits (7 different traits in total) using GLM(M)s in R. The data was collected at very irregular intervals and from 6 different locations. For every location 5-...
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63
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Specifying model in mvabund - is GLMM an option?
I'm looking to use some of the packages in mvabund to do a fourth corner analysis and was wondering if I can use glmm within this package. Everything's been laid ...
- 21
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863
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extending BACI analysis to lme, glm
I am analyzing data from a BACI (before-after, control-impact) design. BACI analyses typically look for changes in the mean response before(B) and after(A) at control(C) and impact(I) sites, but I ...
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2
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1
answer
104
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What is the general process of choosing, confirming, and supporting the distribution used in a generalized linear model?
I am trying to better understand the process of choosing and validating a distribution for a generalized linear model (glm). I understand that for the most part, you can narrow it down to a few ...
- 351
3
votes
1
answer
361
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GLM on non-integer data
I'm looking for a recommendation on what GLM I could do with non-integer data.
Brief background of what I am doing:
I'm wanting to combine calculated herbivory rates with abundance data, to compare ...
3
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1
answer
110
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GLM with random factors for observational design
I would love your help: I have 50 houses where I have counted the number of Mosquito's eggs once a week for 4 months. I have 5 fixed factors (temperature, NDVI, precipitations, etc) and I want to add ...
1
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0
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35
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Modelling resource selection in savanna ungulates
I am amidst an analysis of an 8 year data set that was collected from wildlife surveys over an 8 year period for my MSc thesis. 2 surveys were conducted each season for the three discernible seasons ...
- 293
2
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1
answer
2k
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Multiple testing (bonferroni?) with GLM
Hi everyone: I scored four mutually-exclusive behaviors (e.g. feeding, brooding, standing, preening) on a number of observations of birds in two different treatments, and two different nesting ...
- 101
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2
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346
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What model(s) are appropriate for unbounded species abundance data with 0's and environmental response variables in R?
I am conducting a research project on the vegetation composition of an abandoned mine site to determine the environmental factors that influence species abundance (cover) and composition.
Study ...
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2
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867
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is it possible to use a vector object a dependent variable in GLM?
I would like to write certain model in R.
I would like to o use a vector object as a dependent variable in my general linear model. The model is supposed to explain how some environmental factors, ...
5
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1
answer
229
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Modelling % cover that do not add up to 100% : GLM distribution families
I have an experimental set-up that consists in studying the impact of diversity of plant mixtures on the development of invasive species. On each plot, we recorded the % cover of each species which ...
- 311
1
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0
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165
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Family in GLM - how to choose the right one? [duplicate]
When modeling data sampled in the field, I often come across the problem of determining the Family of the dependend variable for GLM (or GLMM). An example: in an ecological study, I have ~ 60 patches. ...
- 447
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2
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589
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What distribution to use for response variable which is a ratio of counts (that are not independent) where it can be >1?
I have two sets of counts, bat passes and feeding buzzes. A feeding buzz is not independent of a bat pass. In a single bat pass, there can be multiple feeding buzzes. My response variable is buzz ...
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0
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173
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Generalized linear mixed model with time lags
I'm attempting to understand how random variables and one fixed variable are influencing an animal population over time. The trouble I am having is that my population density estimates were only ...
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3
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1k
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Plotting results from a GLM in R [closed]
I'm a complete novice when it comes to stats, so my question may not even be relevant. I have been using the glm() function in R to model a response variable (bird species) versus predictor variables (...
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2
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2
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6k
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Interpreting output of dredge function
I need find which is the best model / variables for explaining the species richness of Coleoptera in Hawaii islands.
This is the input:
...
- 23
4
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1
answer
290
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Multivariate Analysis of Ecological Data: Procrustes analyses or GLM?
I have a dataset containing 6 variables (vegetation cover in percent) and the number of species found in 30 areas.
I would like to test if the different vegetation covers explain species richness.
...
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10
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1
answer
19k
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Interpreting output of dredge
I ran a GLM for the first time in R and am not sure how to interpret the result.
This is the input:
...
- 141
2
votes
1
answer
3k
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GLM - which probability distribution to use for abundance data?
I'm fitting a generalized linear model to try to understand how the abundance of a species of freshwater fish varies in response to some environmental variables. I'm using the AIC to choose between ...
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18
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4
answers
28k
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Interpreting random effect variance in glmer
I'm revising a paper on pollination, where the data are binomially distributed (fruit matures or does not). So I used glmer with one random effect (individual plant)...
- 313
1
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1
answer
1k
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Validity of stepwise regression in DistLM
I have a set of nutrient fluxes data and I would like to know which environmental drivers explains the fluxes. I used DistLM and the marginal test showed that none ...
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1
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105
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Basic question about getting esimated probabilities in R
I've got what I think is a fairly basic problem. I'm not sure if it is a conceptual question or software question, but I'm fairly new to using R and these kinds of stats, so it could be either or both....
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2
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1k
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Population model to model year to year dynamics
My task is to assess how various environmental variables affect annual population fluctuations. For this, I would use a model like:
$$
\mbox{log} ( \mu_{i,j+1} ) = \mbox{log} ( \mu_{i,j} ) + R_{j} + \...
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7
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1
answer
5k
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Species Richness, Dominance and Diversity Differences
I have collected 70 organisms from 4 different sites; two sites of treatment 1 and two sites of treatment 2. I also have a continuous explanatory variable (average temperature) which is different ...
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