Questions tagged [environmental-data]
The environmental-data tag has no usage guidance.
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Adjustment in DLNM - case control setting
I have data in a case-control format with a 5-year lag of exposure. I want to adjust, in addition to the strata, for the number of monitoring stations used to calculate the exposure. The problem is ...
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How do I treat regression when I know that relationships/coefficients will differ between individuals in my dataset?
I have a large dataset made up of 100 climate simulations. Each simulation runs over 100 years and for each year I calculate a handful of metrics (features). I'm interested in measuring how well these ...
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Is the ETS function from forecast appropriate for skewed environmental time series data? does the time-series data need to meet certain criterion? [closed]
I have environmental data that is usually just analysed with the nonparametric man-kendall and sens slope, because it is skewed. Can the ETS function which picks what exponential smoothing model to ...
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What statistical tests to use for multiple datasets?
I have calculated the species richness of mammals in 10 sites, for different variables. For example, I have the species richness of carnivores, omnivores, herbivores etc in one analysis group, and ...
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Parametric or non parametric mixed effect models for very small sample size in ecological/soil data?
I am running an ecological/environmental experiment in a salt marsh with 5 experimental treatments and 3 replicate soil samples taken from each treatment. I have been taking measurements from these ...
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Plotting PCA cordinates as composites of environmental parameters into NMDS ordination of species assemblages
I have conducted a PCA and identified that the principal components (PC) are not driven by a single environmental parameter but are affected by several for each PC. I was then advised to retrieve the ...
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Confused about the censoring procedure in Helsel (2012) book
Reading Helsel STATISTICS FOR CENSORED ENVIRONMENTAL DATA USING MINITAB AND R,
at page xviii the author writes:
The Figure i4 shows concentration (y) levels versus distance (x)
downstream. What ...
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Why is the fully-symmetric bidirectional case-crossover design biased and the semi-symmetric design not when there are time-trends in the exposure?
I am trying to understand why the fully-symmetric bidirectional case-crossover design is biased when there are time trends in the exposure and why the semi-symmetric design is not biased?
I have tried ...
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Formal way to test if a non-linear approach is necessary to correlating environmental variables to NMDS ordination axes?
I've got a follow-up question to this post regarding correlating [non-]linear environmental variables to NMDS ordination axes.
My original plan was to use function ...
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Interpreting NMDS environmental correlations in the context of spatial and temporal autocorrelation
Do I need to account for autocorrelation when assessing correlations of environmental variables on an NMDS (nonmetric multidimensional scaling) ordination of species data? If so, how?
Data + setup:
I'...
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Can I use a GLM in R to analyse the relationship between time-series environmental variables?
I have a water quality sensor which is measuring various parameters every hour for one year in the same location. I would like to analyse the relationship between each of these parameters and ...
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Need to scale environmental variables when correlating to NMDS axes?
I've created a Non-metric MultiDimensional Scaling (NMDS) ordination from a Bray-Curtis dissimilarity matrix. (Starting data were basal areas of various tree species across multiple research plots).
I'...
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Is short vector length in PCA problematic? Why are my points so far from my vectors?
I am using PCA to examine the relationships between environmental factors of a couple of different types (physical properties, concentrations, relative abundance of genes). I have log-transformed the ...
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How to calculate the value (wind direction) of "maximal effect" in a linear-circular correlation?
I am trying to evaluate the effect of wind direction (circular variable) on a dependent linear variable. I have used circular-linear regression to find the correlation coefficient between the two ...
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What is the best correlation test to use when you want to compare two variables in a spatiotemporal context?
I have 9 sampling sites. I did the sampling in May, July, and September in the sediments and the water. So, I have 27 samples. I want to know if there is a linear correlation between total nitrogen ...
