Questions tagged [compositional-data]
Refers to variables representing fractions of a total, i.e. all lying in $[0,1]$ interval and necessarily summing to one. Analysis of such data is often called compositional data analysis.
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Significance of factors/regressors on compositional data
Let's assume that I have composite data, similar to the "ArcticLake" example dataset in the DirichletReg package in R. Now, I would like to know whether various numeric variables and factors ...
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Estimated marginal trends after regression of isometric log ratio transformed compositional data
I have longitudinal compositional data with four base response variables. I would like to compare the slopes of groups across time, but not for the ilr-transformed composition. I wish to compare the ...
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Do I understand correctly how to perform sequential binary partition?
I’m dealing with geochemical data. Let’s say I have the results of chemical analysis of a mineral with elements: A, B, C, X, Y, Z. X, Y and Z are elements belonging to the same group (let’s say they’...
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Inference from profile comparisons
What would be a good test to compare patterns of differences among treatments? For example, the Y maze has an outcome of % of entries into each of three arms. Thus, three numbers are generated for ...
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Multivariate analysis with lmer and lmerTest
I'm dealing with compositional data (data that sum to 1). They are inherently multivariate. One way to analyse compositional data is with a ilr (isometric log-ratio) transformation. I'm following the ...
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Compositional data - interpreting Dirichlet regression with interactions
I did a Dirichlet Regression to assess the effect of independent variables on a compositional dependent variable. However, as I have 3 predictors, I do get interaction.
I have a hard time ...
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Analyzing compositional data (sum of proportions = 1) using mixed models with explanatory variables for each proportion
I aim to investigate how the relative abundance of species across communities is associated with the functional traits of each species. For each location ($>250$), I have compositional data that ...
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R - multinomial logistic regression with relative frequencies as response variable
My colleagues observed in an experiment involving categorical and continuous independent variables, how the species composition changes. Approximately equal numbers of microbes were used in the ...
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How do I compare explanatory power of Dirichlet regression with other models?
I have a dataset with 7 variables expressed in % of the total (i.e. one of the constraints is that sum of the variables = 100%).
I am looking at Dirichlet regression in R for the first time (I am ...
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Principal Component Analysis (PCA) the constant sum constraint [closed]
I have data that sums to 100 % +/- 5%, and I was reading that data that sums to 100% should be altered before doing PCA. A method that I found others have done is to use the centered log-ratio (clr) ...
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Comparing distribution of continuous data and binned data that are compositional
The Data
I have a list of N ∼ 6700 population members who have a condition and are labeled with age in whole years and biological sex.
For the parent population, I have
The total number of each sex (∼...
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"Reference" Continuous Variable / Variables that are perfectly multicolinear and sum to 1
I am conducting an ecological study that has data on municipalities as a sample. In this data, I have bins with proportions of individuals within a certain category that resides there, for example, % ...
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Scaling and centring in PCA of compositional data
I am following this review's approach for PCA using compositional data. It involves computing the centred log-ratio (CLR) transformation of the compositional data, and then running PCA on the ...
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Compositional data analysis - counts and proportions
I have a dataset where I counted monkeys in 10 plots and assesses the proportion of 5 different habitat types covering the plot. The sum of the habitats per plot is always 100.
I would like to test ...
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Any reasons I shouldn't calculate the difference between CLR transformed variables to analyze my data in a time-independent way?
First time posting, so apologies for any missing info and the like.
I have some microbiome data collected from two different treatment groups over two timepoints. I want to look at the compositional ...
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