Questions tagged [correspondence-analysis]

Correspondence analysis is a dimensionality-reduction and mapping technique for nominal variables. It is often applied to a contingency table to explore visually affinities among row and column categories. If a table is 3+ dimensional the analysis is called Multiple Correspondence analysis.

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11 views

Using MCA/PCA together?

If I have a large dataset with continuous, discrete, and categorical data, is it appropriate to use MCA on the categorical features and PCA on the continuous, separately? I'm preprocessing my data ...
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How to pool variables that rarely occur, particularly with respect to survey data

From the text : Multiple Correspondents Analysis by Brigette LeRoux very infrequent categories of active variables need to be pooled with others when feasible The text doesn't explain how this ...
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How many observations need to be in place for multiple correspondence analysis with a particular number of questions/categories

I'm wondering about how many observations need to be in place for a particular set of questions. If I have data as follows: ...
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Multiple correspondence analysis, definition of distance between two categories of the same question

From the text : Multiple Correspondents Analysis by Brigette LeRoux The data for this quesiton is: The definition of $f_k$ is $f_k = n_k/n$ where $n$ is the total number of individuals and $n_k$ ...
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Intuition about how the formula for “variance of axis of angle $\alpha$ with horizontal axis” works (multiple correspondents analysis)

From the text : Multiple Correspondents Analysis by Brigette LeRoux the following is given (page 32). For the purposes of this post I'm just considering there to be two dimensions that point clouds ...
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19 views

Ranking groups based on multiple criteria

My objective: To give a more sound foundation to the data I have access to. This is an exercise that is aimed to look for some structure and soundness in the interpretation of the data BUT it can be ...
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63 views

Input data for Canonical Correspondence Analysis (CCA)

I'm going to conduct Canonical Correspondence Analysis (CCA). In the tutorial I've found at: CCA environmental data are discrete ...
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28 views

Detrended Correspondence Analysis or Non-metric multidimensional scaling

For an ecology project I am analysing how and if the species composition of a habitat type (heathland for example) changes through time. This was done by measuring fixed plots within a habitat type ...
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Difference between two groups of people, each person “is” several characteristics

I have two groups of people, A and B (let's say 15 and 25 people). Each person in each group is characterized by a bucket of features (bucket = 6-18 features). Each feature, during qualitative phase ...
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identifying what has changed in the data year on year

I have a dataset from one year and the 'same' dataset for the next year. I would like to identify what has changed in the datasets between the years. Both datasets have the same columns. I currently ...
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63 views

How to conduct a principal component analysis on data set with large number of zeros

I have data for percentage cover of plant species in 500 sites. There are columns for 30 different species in the data set and I would like to drastically reduce this down to a manageable number of ...
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MCA output analysis

I am quite lost on how to interpret the output of an MCA analysis. What does a the output of $var$v.test, $var$contrib, $var$cos2 and $var$coord mean respectively? In addition, I don't quite ...
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Multiple Correspondence Analysis -Decision Making Index Stata

I am trying to make a decision making index using MCA. I am using 6 binary variables and the responses are whether the respondent makes these different decisions alone. I read once somewhere the MCA ...
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Display of dimensions in (multiple) correspondence analysis

I am getting into correspondence analysis and was wondering what the correct way is to display more than two dimensions in a biplot. I found examples with biplots showing dimensions plotted in order (...
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32 views

PCA/ordination/Correspondence analysis for data with two groupings

I am working with a data set on plant presence-absence within 40 plots. For two years, the presence-absence of all plants were noted in each plot. I would now like to investigate whether the plant ...
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54 views

Interpreting Multiple Correspondence Analysis Output

I have the following data for Maryland and Virginia with six different capacity types along with what score (1, 3, or 5) each person grades that capacity type. Essentially what I want to do is see if ...
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What assumptions about the data are require for Multiple Correspondence Analysis?

In multiple correspondence analysis, what assumptions about the data are necessary in order to find the principal coordinates for the rows and columns?
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Coding a categorical variable: 0-1 or multiple subcategories?

I'm working with R and want to run a correspondance analysis on a dataset containing, among the others, the following factors: city district: 27 levels, each corresponding to a given district ...
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How to determine which species are biggest contributors to overall variation in community?

I have data on the community of microbes from different soil types, however I do not have any environmental variables, only categorical (sites). I have generated PCoAs with distance matrices, however ...
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Having only binary variables, why is the use of PCA still appropriate?

I often see the use of PCA on large datasets with a lot of binary variables. As i recall, the computation of the principal components is done via eigenvalue decomposition (or SVD) of the correlation ...
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97 views

One-hot encoding for SOM

I have a question regarding how I should convert categorical data to numerical data. I'm using this kdd99cup intrusion detection dataset, which has a 41 attributes and class label is the type of ...
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950 views

Is MCA equivalent to PCA when all variables are binary?

I am looking to apply principal component analysis on binary (true/false) data, and I have come across the "equivalence between PCA and MCA" (Multiple Correspondense Analysis) for binary data, but ...
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183 views

Canonical Correspondence Analysis: how to interpret results

I am using Canonical Correspondence Analysis (CCA) to analyze phytolith abundances (similar to pollen) over environmental gradients. As I am new to CCA, I read some background info. The following ...
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883 views

R vegan: RDA vs CCA, which test to answer my research question and which results to report?

(if my question should be cut up into sub-questions please let me know, since all those questions are related I decided to ask them here together as one long question) Main question As part of my ...
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I have done crosstabs and a Correspondence Analysis, having trouble reporting and interpreting Chi-Squared and Inertia?

I have data on 1500 cases with two variables (color, genus) with 5 colors and 6 genera. I almost had generally equal spread across genus, but one is disproportionately represented and has about twice ...
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194 views

What do to after hierarchical clustering and finding number of clusters

I have a dataset with 10 categorical variables with over 5000 observations, I have clustered and then found the optimal number of clusters using elbow method. Now I'm not sure what to do because I'm ...
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162 views

Is Multiple Correspondence Analysis applicable to Multi-valued Categorical Variables?

I have a data-set containing only Categorical Variables. I needed to do Principal Component Analysis on the data set. Eventually, I found Multiple Correspondence Analysis and learnt it. But, in MCA, ...
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270 views

Is there a specific name for this plot?

This plot represents the popularity of technologies in two "tools", vue and react. In left-top corner are specific technologies for vue but not for react, right-top technologies popular in both tools ...
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287 views

How I interpretate a CCA plot (made with xlstat)?

Here are the 2 CCA (Canonical Correspondence Analysis) plot I'm trying to interpretate. I did them using the appropriate function in xlstat. I want to know how I should interpretate the fact that in ...
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246 views

CCA (Canonical Correspondence Analysis) - Which version of the dataset is more adequate?

I'm currently working on a dataset of +400 samples, with 2 quantitative variables (salinity and depth) and 2 qualitative ones (sequencing method performed and nature of the sample, sediment or water) ...
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162 views

How to perform CCA with block design in R

Following example and data are completely fabricated: Suppose I am studying grooming behaviour in apes. I have four cages, 8 apes in each (4 females + males). For 24 hours I did an observations with ...
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103 views

What in cross validation from co-correspondence analysis indicates sufficient axes numbers?

The coca function at cocorresp package disponible for R provides a predictive way to relate two biological composition datasets. I need help to understand one step from examples on documentation ...
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48 views

No departure from independence term in constrained correspondence analysis

I am used to think of correspondence analysis (CA) as dissecting the weighted departure from independence through singular value decomposition, but I cannot relate this to constrained correspondence ...
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170 views

How variables (constrained loadings) are selected in a biplot CCA

I am trying to do a Canonical correspondence analysis (CCA) using the community data and chemical data. I have my family level taxonomic data as community data. In chemical data I have 18 variables: ...
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248 views

Should PERMANOVA be used to select factors for Canonical Correspondence Analysis?

I am interested in investigating the relationship between species composition and several environmental factors. My question is whether it is appropriate to use PERMANOVA to select a 'best' ...
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361 views

How to analyse multiple choice and overlapping questions in MCA?

I need to analyze a survey about entrepreneurship which has around 50 categorical variables. Therefore, after some univariate analysis, I want to apply Multiple Correspondence Analysis (MCA) in order ...
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72 views

Can Y-aware PCA be performed with binary independent variables?

I came across this tutorial for Y-aware PCA using the vtreat R package. In short, Y-aware PCA is PCA on variables that have been scaled to be in y-units. Is it valid to scale categorical independent ...
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Is there an analog to logit Y-aware PCA for correspondence analysis?

I came across this tutorial of logit Y-aware PCA for dichotomous $Y$s. Does anyone know if there is an analogous procedure for correspondence analysis? It seems that there couldn't be since the Y-...
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187 views

Multiple correspondence analysis for clustering (unsupervised learning) [closed]

I have limited stat/coding knowledge yet I try to do user clustering using unsupervised method using R. I have about 2795 observations gained from survey (mixture of categorical and scale questions). ...
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524 views

R multiple correspondence analysis loadings

I'm running a multiple correspondence analysis in R using the FactoMineR package: ...
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203 views

Displaying large number of text labels on a scatter plot

Having too many species in the data, makes the species labels overlap in a plot of a canonical correspondence analysis. This makes it difficult to interpret. Is there a reasonable possible solution? ...
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318 views

Correspondence analysis vs chi square

My data: ...
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1answer
777 views

Assumptions for Canonical Correspondence analysis

I have been trying to find the major assumptions a Canonical Correspondence Analysis makes when doing its analysis. I have had a hard time finding anything useful. I did, however, find the assumptions ...
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343 views

Do I need to standardize environmental data before canonical correspondence analysis?

I have a dataset of 15 environmental variables (soil physical and chemical properties) and about 25 "species" variables for about 40 sampling sites. I want to do a CCA to analyse the effects of the ...
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69 views

How to test for the effects of plant community composition on insect community composition whilst controlling for geographic distance?

I'm trying to test for the effects of plant community composition on insect community composition using ordination, but I need to control for geographic distance. I know CCA can handle three matrices ...
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52 views

Minimize shared variance of columns between factors in Correspondence Analysis

I am using correspondence analysis (CA) to analyze a contingency table. In the columns I have statements about some brands (characteristics) and in the rows I have the brands. My aim is to obtain in ...
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490 views

CCA species coordinates relative to ordination surface

I want to display species coordinates relative to an environmental variable using ordination surface (ordisurf in vegan package)...
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177 views

I want to run a same result of biplot in R

There is a software called Brandmap$^1$ which can return a biplot from a matrix. I am trying to run the same result in R but the coordinates are not the same. First I input a simple matrix into the ...
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104 views

It is possible to apply correspondence analysis to a 2x2 contigency table?

I was wondering if it is possible to apply correspondence analysis to a 2x2 contingency table. Since that correspondence analysis is a method for dimensionality reduction, I think it is necessary to ...