# 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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### Anomaly detection using reconstruction error (compositional data)

I have compositional data (nonnegative and sum to 1) in a data matrix with 150 samples (rows) and 4096 features (columns). The data is made up of 144 normal samples and 6 known anomalies, which I'm ...
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### Combination of correlations: How to correlate compositions?

How to correlate a set of compositions to a same-sized set of estimates of these compositions? -> composition(estimated) vs composition(real) Imagine you have a mixture of 5 liquids A+B+C+D+E, ...
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### How can I calculate principal components scores in a compositional data PCA?

I hope someone can help. Please let me know if my question is not clear. I have compositional data, where there are three variables which sum to 100% for each row, something like this: ...
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### neural network estimation of compositions distribution

To use feed forward neural network to predict compositional distribution, e.g.fractions of nutritions, vitamin 10%, protein 35%, water 35%, salt 20%, for each composition sample, sum composition ...
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### Calculating distance with compositional and non-compositional data

I have demographic data across different districts/neighbourhoods, and would like to find, for a given district, which is its most similar peer district across multiple variables such as size (total ...
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### Modeling probability mass over time for prediction

Consider a discrete random variable $X$ with three possible realizations $x_1,x_2,x_3$. This variable is observed over time, with the number of observations per point in time varying. The top ...
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### power calculation for cox proportional hazard regression

I am trying to perform a statistical power calculation for cox regression. we want to investigate the association of composition (that has 4 variables) and sickness absence events in the future. for ...
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### What to do when predictors are proportions that sum up to one?

I have a situation as the one described in the links below: Interpreting proportions that sum to one as independent variables in linear regression Predictor variables sum up to 1 but not necessarily ...
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### Regression model not fully ranked

I am running a linear regression model with about 5000 cases. The dependent variable is income at closure an interval variable. I have run this model without problem many times. Now I am adding 9 new ...
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### survival probability to proportional hazard ratios in r

I am using Cox proportional hazard regression to determine the association between physical behaviors (physical activity, sedentary behavior, and sleep) and mortality. to elaborate on these results, I ...
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### Analyze categorical data when there cannot be “negative” influence

Suppose there are 1000 items given 5 labels [A,B,C,D,E]. You observe [750,200,25,25,0]. You want to find out whether items are biased towards being given certain labels. In a standard chi-squared ...
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### Predict a vector of values with constraints? [duplicate]

I am aware of a variety of methods for simultaneously predicting multiple outcomes known sometimes as multivariate regression/analysis. However, my situation is a little more special. I am trying to ...
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### What is the most appropriate transformation method for performing analyses on species composition data?

I would like to compare differences in fish diets between sampling sites using a Bray-Curtis dissimilarity matrix and non-metric multidimensional scaling techniques. My raw data consists of counts of ...
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### Permutation testing for simulated compositional data

I'm testing some methods for estimating correlation in compositional data. As part of this process, I'm using the following approach: simulate un-normalized features $Y$ normalize features for each ...
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### What type of chart is this? A crossing stacked area chart?

The New York Times made some beautiful visualizations of energy consumption by state: link What would this type of chart be called? A cross-stacked area chart? Does anyone know any libraries or ...
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### Peanut butter jars full of river mud and bacteria?

I'm an environmental scientist looking into dynamics of bacteria growth in river bed sediments. I collected lots of data, and used regression for most of the comparisons, but one (the most important) ...
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### Compositional Data and Machine Learning

One of my features is compositional of nature, represented by a vector [p1, p2, p3]. Each vector represents an emotion and each vector sums up to unity. Eg: ...
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### Compositional data analysis - what's the “method”?

Let $\textbf{X} = (X_1, \ldots, X_n)$ be a vector of responses, where $X_i = (p_1, \ldots, p_k)$ is itself a vector of probabilities. What method does one use to analyze such data? I want the logic/...
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### Overview of compositional data analysis

I just need a very short summary of what the standard way to deal with compositional data is. I've skimmed pages in a 500-page long book on the topic, and I didn't really gather much. I would like ...
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### Applied logratio analysis. Where do you learn it?

I want to analyze compositional data using R. Dirichlet regression has been proposed, but the logratio analysis methods seem to constitute a more complete and well-tested approach, so I want to learn ...