Statistical Analysis Stack Exchange
Statistical Analysis Stack Exchange

Questions tagged [ecology]

Ecology is the study of how organisms interact with their environment & each other. Ecology uses some specialized statistical techniques (eg ordination methods). Use this tag to indicate applications of statistics that are unique to ecology or that require a recognition of the ecological context.

Ecology is the subdiscipline within biology that studies how organisms and species interact with their environment and with each other. Exploratory and multivariate statistics, often called 'ordination methods', are common in ecology.

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What is the "horseshoe effect" and/or the "arch effect" in PCA / correspondence analysis?

There are many techniques in ecological statistics for exploratory data analysis of multidimensional data. These are called 'ordination' techniques. Many are the same or closely related to common techniques elsewhere in statistics. Perhaps the…
gung - Reinstate Monica
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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) and one fixed effect (treatment). A reviewer wants to know whether plant had an…
jwb4
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Question about logistic regression

I want to run a binary logistic regression to model the presence or absence of conflict (dependent variable) from a set of independent variables over a 10 year period (1997-2006), with each year having 107 observations. My independents are: land…
Stephen
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Analysed non-linear data with GAM regression, but reviewer has suggested fitting exponential or logarithmic curves instead. Which to use?

I am trying to publish my Masters thesis which looked at elephant impacts on vegetation, with a focus on the effect of artificial waterholes. I have made my initial submission and am now performing major revision, which involves some questioning of…
Luke Wilson
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What is the distribution of the error around logistic growth data?

In ecology, we often use the logistic growth equation: $$ N_t = \frac{ K N_0 e^{rt} }{K + N_0 e^{rt-1}} $$ or $$ N_t = \frac{ K N_0}{N_0 + (K -N_0)e^{-rt}} $$ where $K$ is the carrying capacity (maximum density reached), $N_0$ is the initial…
Etienne Low-Décarie
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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: global.modelAcar <- lm(Acar ~ logNutrientsc*logNDSc*logNNNc, data = dat) summary(global.modelAcar) options(na.action=na.fail) MAcar <-…
GoldFire
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What criteria to use for separating variables into explanatory variables and responses for ordination methods in ecology?

I have different variables that interact within a population. Basically I have been doing an inventory of millipedes and measuring some other values of the terrain, like: The species and the amount of specimens collected The different environments…
Leonardo
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How to construct quadrats for point processes that differ greatly in frequency?

I want to perform quadrat count analysis on several point processes (or one marked point process), to then apply some dimensionality reduction techniques. The marks are not identically distributed, i.e., some marks are appearing quite often, and…
Wookai
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Books on statistical ecology?

I know this question was asked before: Reference book for ecological studies but it is not what I am looking for. What I am looking for is if anyone could recommend a good book (or a canonical reference) on statistical ecology? I have a very good…
user25658
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Does using box-cox transformation on individual data sets prevent these data from being comparable?

I have been using the box-cox transformation to normalise data for input to an Ecological Niche Factor Analysis software, as recommended by the software creators. However, it has occurred to me that the box-cox transformation method has (obviously!)…
JSnf2012
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Variance of a distribution of multi-level categorical data

I am currently analyzing large data sets with various characteristics (such as city). I wanted to find a measure which would essentially say how much or how little of a variance there was across the data. This would be much more useful than simply…
Eric Staner
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Can I test for correlation between variables before standardize them?

What I want to do is to construct GLMM's to evaluate resource selection, and I have a set of variables (some representing distances and others representing % of land cover). Can I test for correlation between variables before standardize them? I am…
mtao
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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} + \sum\limits_{k} \alpha_k x_{k,j} \\ N_{i,j} \sim…
Tomas
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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 it is a binomial link, as the output is not a…
parallax
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Principal component analysis with group data

In my experiment I have used 30 different accessions of a species. One group is challenged drought and the other group is control. I have collected data on 6 different parameters. I want to know which accession is more tolerant or susceptible, which…
Golam Dastogeer
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