# 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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### Determining the correct compositional class for R package "compositions"

I am currently struggling to define the correct class of compositional data for my data. It consists of durations (in minutes) in specific areas of an arena and is limited by a maximum duration (...
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### Investigating significant difference in composition between years

I want to investigate if there is a difference in the trophic composition of fisheries landing data between years. I have several years of data and I have the raw weight of each trophic group for each ...
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### Compositional Data in R

I'm writing a work on the Aitchison geometry for compositional data and I have seen an Image I want to reproduce in R. I work with the "compositions" library and I want to understand how to ...
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### centered log ratio transformation of overlapping compositions

I have a total of $N$ units that are assigned to $D$ classes based on certain combinations of characteristics. If each unit is assigned to only one class, then the problem reduces to the usual ...
1 vote
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### How to fit a Dirichlet mixed effect model in R?

I have a compositional data from an arena experiment in which the duration of an animal in specific zones was denoted. The time in the arena was fixed for all individuals which makes the durations ...
74 views

### How does removal of symmetry (e.g. via constraints) in a Bayesian optimization search space affect search efficiency?

There are many examples of search space symmetry in real-world optimization problems in the physical sciences. To motivate this, here are some that come to mind: When optimizing a formulation such as ...
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### Compositional data analysis with rounded values: validity of log ratio methods

I want to use histopathology compositional data with percentage rounded in 10% increments (for example 4 classes percentages: 0% - 50% - 30% - 20%). I am interested in data exploration (e.g. PCA, CCA) ...
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### Compare paired before and after composition proportions

I have some data on the composition of purchases by households, before and after an intervention. This composition is known at the number of items or amount spent level within 7 categories, and can be ...
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### Correlation of variables in constrained sum

I had an exercise this weekend that was as follow: Take 2 random variables X and Y iid and following a normal distribution (mu = ...
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### What is the best imputation method for missing values in compositional data?

I'm a little newbie at statistics, so I'm sorry if my question is too dumb. I'm working with compositional datasets with several chemical elements (continuous data; arranged in columns), but also some ...
1 vote
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### Multiple imputation of a compositional score. Which variables should be included?

My outcome is a disease activity score (i.e., compositional score) called the ASDAS-CRP, which consists of patient-reported outcomes and CRP (i.e., a serum marker of inflammation). I have read Stef ...
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### Is it necessary to transform a compositional predictor variable with Generalized Liner Models

I am reviewing an association study in which the primary analysis consists of using covariate-adjusted regression models to identify associations between microbiome taxon abundances and host ...
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### Compositional data: is it possible to make products of components/features in a composition?

I've never asked about Stack OverFlow, even though it's been so useful to me on many occasions! I'm sorry if this topic has already been discussed previously, perhaps I wasn't able to find the good ...
1 vote
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### Continuous independent variables that sum up to 100%

As I am studying the capital structure of firms, the total of proportions owned by different ownership types (free float, institutional ownership ... etc.) will be 100% of the company shares. In my ...
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### Performing Isometric Log-Ratio Transformation with an amalgamation of multivariate data

I have a multivariate compositional dataset with data referring to a district. The dataset comes mainly from census sources and I would like to apply statistical clustering on this data. Many columns ...
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### How do I conduct a PCA on compositional data in R

Compositional data are multinomial vectors that add up to 1 or 100 (for composition expressed in percent). Aitchison (1983) recommended an inverse logit transform (or link function) for these data (ln(...
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### How do I interpret Isometric Log Ratio regression coefficients using lmCoDaX in robCompositions

I am using the lmCoDaX command in R robCompositions to estimate the effect of land cover on a response variable. The covariates are percentages range from .001 to 1 such that the four sum to 1. e.g.(1 ...
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### Is it OK to transform non-normal proportional data

I have a dataset for 'time spent' (hours) carrying out 'behaviours' (walking, lying, standing, grazing), during day or night 'periods' of cattle. Time spent is my dependent variable, with behaviours ...
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### How to apply compositional regression to new data in R?

My goal is to fit a linear regression to compositional data and make the model for some predictions. I am able to create the model not sure how to apply it to new data. Here is an example I created in ...
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### Machine learning algorithm to produce compositional data results?

I have some unlabeled data and I am trying to train an algorithm to find different components in them and produce some compositional data vectors for each component. Each data entry looks like an ...
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### Composition data and difference between groups

I have a problem that can summarize: Is there a difference between stores in terms of the share of sales percentage in the 4th quarter. ...
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### How to model choice among three quantities, subject to a constraint

I have a response variable that is the amount in monetary units (m.u.) that a person can choose to donate among three alternatives, subject to a constraint that the total amount should be equal to 100 ...
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### Log-ratio transformations, Aitchison Geometry, why logs?

I'm recently diving into the field of compositional data analysis and I'm still wondering why the log transformations that Aitchison proposes work. What I understand is that, having a $D$- part ...
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### Replacement of true zeros in compositional data

How does one go about replacing true zeros in compositional data sets? There is a lot of information on handling rounded zeros, such as multiplicative replacement (MultRepl in R), but not on true ...
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### Compositional data analysis

I have one independent categorical variable "Period" (day or night) and 4 dependent continuous variables "Behaviours" (walking, lying, standing, grazing) which are compositional in ...
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### GLM using proportions/percentage response variables

I have a dataset for time (hours decimal format) spent carrying out different behaviours of cattle in a day. I'm trying to run a general linear mixed model with two independent variables (lactation ...
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### I'm looking for a statistical test more robust than the sign test for my experimental analysis

I made an exploratory experiment that consists of a pair of readings. I used Scanning Electron Microscopy-Energy Dispersive Spectroscopy (SEM-EDS) to read elements on several mineral surfaces, getting ...
1 vote
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### Should I use Linear Regression in this case?

I'm doing a personal project on regression and I hope I can get some advice from you on several problems. The dataset I'm having is about cuisine, shape is 180x9, and the 2 continuous variables are &...
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### Using compositional data analysis to represent chemical compounds

I've recently got some insights about compositional data analysis, wondering whether it could be suitable for the framework I'm currently in. Recently, I've been very interested in trying to find some ...
1 vote
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### Compositional Data with Time Series

I have time series data corresponding to different entities. My goal is to train a model on the set of entities I have, and then provided a new entity to predict the whole time series for it. For ...
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### Non-logarithmic approaches to compositional data

Background Compositional data ($x_i>0, \sum_i x_i=c$) are usually analyzed using some kind of log-transformation (alr/clr/ilr), to take into account naturally the fact that, in presence of the sum ...
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I'm fitting a model using Bayesian MCMC. The model parameters include a parameter vector $\beta$ which is assumed to reside on a simplex $$S^d=\left\{ \beta=(\beta_1,\beta_2,\cdots,\beta_d);\space \... 2 votes 0 answers 102 views ### Can I use compositional data in a GLM? I have landing data (kg) of five species where I try to identify which factors may be contributing most strongly to the high catch. Before, I had 4 predictor variables (Depth, Chlorophyll, Temperature ... 2 votes 1 answer 190 views ### How to calculate percent similarity between two sets of compositional data I have data that is in the form: ... 0 votes 0 answers 43 views ### Bayesian compositional regression using ilr I'm trying to fit a compositional data regression from a Bayesian perspective and using ilr coordinates. Once the ilr is computed for the response variable, a multivariate Gaussian regression has to ... 1 vote 0 answers 16 views ### How to model proportional data of >2 categories on continuous predictor variables I am trying to model data in which I have 2 continuous predictors and a proportional response, but it isn't a single proportional value, but rather 5 different categories, whose proportions all sum up ... 1 vote 0 answers 57 views ### transformation or GLM approaches for compositional explanatory variables and a fractional outcome I have a model where the outcome y \in (0,1) is a share variable. The four explanatory variables x_1,x_2,x_3,x_4 are compositional, so they sum to one. They are also all in (0,1). My goal is to ... 0 votes 0 answers 74 views ### Which algorithm suits for classification of multivariate time series data? I have multivariate time series data, where the goal is to predict a binary label, which is changing in time. For illustration: there are 20 individuals, for each of them I measure 50 values (... 1 vote 0 answers 56 views ### Is difference in relative data (compositional data) is still a a compositional data? The table below shows an example of relative data collected in two different time steps: Y is an independent variable that is not part of the composition. The goal is to study the regression between ... 2 votes 0 answers 128 views ### Compositional Data Analysis: What is the connection between Soft-max Regression / Logistic Regression and Linear Regression in the Simplex Space? As someone just learning Compositional Data Analysis, my understanding is the following: The sample space for Compositional Data Analysis is the Simplex Space. Useful transformations like ALR/ILR/CLR ... 0 votes 1 answer 98 views ### What is the probability that a parameter is greater than other parameters given we know the posterior distribution Suppose that we have have some form of compositional data x_i, i\in[1, n] which we propose comes from a Dirichlet distribution such that$$ x_i \sim \mbox{Dir}(\lambda \alpha), where \$x_i=(x_1^{(i)...
1 vote
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I ran a study with a constant sum question: participants had to divide 100 units (I called the units USD) between 5 possibilities. In other words, they had to bet on five possibilities: 1 object out ...
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### How do I use a distribution as an independent variable in a regression?

I'm trying to build a regression model that predicts Trump's vote share in a county in the 2016 election, given demographic data about that county. One of the demographic variables I would like to use ...
1 vote
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### Test for paired proportion data

I want to test for differences in the connectivity of two different brain regions (A and B) measured in 100 subjects. For each brain region, I have measured connectivity to 150 other brain regions (i....
65 views

### How to make correlation test with compositional data?

I have a compositional data set ...
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### Error with the Geometric Bayesian multiplicative replacement of count zeros with "cmultRepl"

I'm new with the treatment of compositional data and I'm working with a microbiome dataset which contains 107 observations and 3246 variables. I'm trying to use the ...
1 vote
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### How to correlate closed data?

could anyone help me with a correlational analysis between compositional variables and non-compositional ones. To make it clear I am interested in the correlations between the shares of employees in ...
1 vote
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### Various variable types in regression

so I have data containing various variable types and I would like to fit a regression model. However as the types of variables are different, I do not know how to deal with it: I mean, there are ...
1 vote