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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153
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6answers
149k views

Can principal component analysis be applied to datasets containing a mix of continuous and categorical variables?

I have a dataset that has both continuous and categorical data. I am analyzing by using PCA and am wondering if it is fine to include the categorical variables as a part of the analysis. My ...
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3answers
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Would PCA work for boolean (binary) data types?

I want to reduce the dimensionality of higher order systems and capture most of the covariance on a preferably 2 dimensional or 1 dimensional field. I understand this can be done via principal ...
38
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1answer
13k views

PCA and Correspondence analysis in their relation to Biplot

Biplot is often used to display results of principal component analysis (and of related techniques). It is a dual or overlay scatterplot showing component loadings and component scores simultaneously. ...
20
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1answer
8k views

What is the “horseshoe effect” and/or the “arch effect” in PCA / correspondence analysis?

There are many techniques in ecological statistics for exploratory data analysis of multidimensional data. These are called 'ordination' techniques. Many are the same or closely related to common ...
19
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1answer
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Interpreting 2D correspondence analysis plots

I've been searching the internet far and wide... I have yet to find a really good overview of how to interpret 2D correspondence analysis plots. Could someone offer some advice on interpreting the ...
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2answers
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What is French data analysis?

Some statistical methods - I do not remember if it is principal component analysis or something like that - are sometimes called "French data analysis". What is it exactly ? And some people say that ...
9
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1answer
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What criteria to use for separating variables into explanatory variables and responses for ordination methods in ecology?

I have different variables that interact within a population. Basically I have been doing an inventory of millipedes and measuring some other values of the terrain, like: The species and the amount ...
9
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1answer
7k views

Using principal components analysis vs correspondence analysis

I am analyzing a data set concerning intertidal communities. The data are percent cover (of seaweed, barnacles, mussels, etc) in quadrats. I am used to thinking about correspondence analysis (CA) in ...
9
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1answer
4k views

Discrete data & alternatives to PCA

I have a dataset of discrete (ordinal, meristic, and nominal) variables describing morphological wing characters on several closely related species of insects. What I'm looking to do is conduct some ...
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3answers
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Dimension reduction techniques for very small sample sizes

I have 21 socio-economic and attitudinal macro-level variables (such as percentage of mothers aged 24-54 not employed, percentage of children aged 3-5 in nursery schools and so on). I also have data ...
7
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1answer
3k views

Difference between canonical correpondence analysis and canonical correlation analysis

I am bit confused between two terms Canonical Correpondence Analysis and Canonical Correlation Analysis. Are the two some how related or they are entirely different techniques? Do they point to ...
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2answers
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Factor analysis for ordinal variables that have different categories

I have a data set that contains about 40 categorical variables that are taken as independent variables (and believed to be related to some unobservable human resource factors) and 4 categorical ...
6
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4answers
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Clustering binary categorical data

I have some data where I have certain classes (c1, c2, c3, c4 ...) and the data comprises of binary vectors where 1 and 0 denote that an entry belongs to a class or not. The number of classes will be >...
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1answer
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Interpreting 2D correspondence analysis plots (Part II)

I'd like to ensure that I understand the process correctly. This is a follow-up question to Interpreting 2D correspondence analysis plots ...
5
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1answer
272 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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2answers
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Correspondence analysis for a three-way contingency table

I'm wondering how to proceed to perform Canonical Correspondence Analysis and Multiple Correspondence Analysis in R on the following three-way contingency table ...
5
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1answer
169 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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3answers
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Whether to use factor analysis based on binary multiple response data?

I have a survey where I have asked people which type of computer games they enjoy and whether they consider themselves a hardcore gamer. I allowed people to select multiple genres, but now I am unsure ...
4
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1answer
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(Multiple) Correspondence Analysis for count data entered as binary variables

I have a data set, 1014 cases and 55 variables which are binary and is in the form of ...
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2answers
5k views

How to best display crosstab data?

I have a 10x10 matrix composed of two variables with 10 brands each. One variable is the brand purchased, the other is the brand considered. My matrix shows a crosstabulation between the two. I need ...
4
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2answers
181 views

Problems with representing and analysing non-network data as a network?

Suppose I have a dataset with 200 observations of 30 categorical variables. The dataset describes websites and different kinds of design features they deploy (or do not deploy). If I were to convert ...
4
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1answer
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Interpreting multiple correspondence analysis

I am interested in exploring how different characteristics of national pension systems are related to each other. I have used MCA for a dataset in which the rows are countries and the columns are ...
4
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1answer
1k views

Ecological modelling: multivariate abundance time-series data

I am working with a dataset that consists of abundance counts of 6 microbial taxa in a lake measured weekly for 20 weeks. I also have environmental data (temperature, nutrient concentrations, ...
4
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1answer
3k views

How best to normalize count data to compare two distributions

Say I have a vector of length 1000. At each position (1 ... 1000) there is a count. I have two vectors with different range of counts such that in vector A the maximum number of counts at a position ...
3
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3answers
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Regression with an unknown dependent variable - estimating “likelihood” to do something

This probably seems like a really strange question, but let me try to explain what I want to do; hopefully it will make sense. I have a data set with a couple dozen variables, such as age, level of ...
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4answers
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Grouping samples by clustering or PCA

If I have 5 binary variables with values for 100 observations to give me a 5x100 matrix. ...
3
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3answers
5k views

How to cluster survey data?

I have designed a rather long (250 Qn) survey designed to uncover user clusters. The questions are such that the pattern of answering should elicit user clusters, but I am having trouble uncovering ...
3
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3answers
219 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 ...
3
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2answers
426 views

Mathematical formulation of correspondence analysis?

From a website you can think that Correspondence Analysis is a categorical data version of PCA. But the main usage of Correspondence Analysis is different from that of PCA, and it is more like ...
3
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1answer
214 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? ...
3
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1answer
544 views

How to interpret this correspondence analysis plot with individuals as nominal variable?

Background: Although correspondence analysis is used mainly for visualizing similarities of categories of two or more nominal variables, I tried following: 39 students (from the same survey as in this ...
3
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1answer
149 views

Statistical Measure for Bidirectional Relationships

I have a karma website where you can create a topic and someone can upvote the topic once. People who receive upvotes from another individual tend to upvote topics from the other individual. What is ...
3
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1answer
663 views

How to choose asymmetric biplots in correspondence analysis

I have categorical data on Police Stations against Crime categories on a 2-way contingency table. I have an asymmetric row map and column map from correspondence analysis using XLSTAT. Which one of ...
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0answers
51 views

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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0answers
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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 ...
2
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1answer
9k views

interpreting NMDS ordinations that show both samples and species

I am using the vegan package in R to plot non-metric multidimensional scaling (NMDS) ordinations. I am using this package because of its compatibility with common ...
2
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1answer
503 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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2answers
4k views

How can one interpret the Stata output for Multiple Correspondence Analysis?

As an alternative to conducting exploratory factor analysis on a set of data, with binary responses, I have been suggested to use Multiple Correspondence Analysis (MCA). Following is a curtailed and ...
2
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1answer
87 views

What statistics could an online book store use? [closed]

This is a theoretical question. If I had an online bookstore what kind of statistics would I keep. The number of times a book was viewed is one example. Another example may be the number of visitors ...
2
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1answer
1k views

How to factor analyze two binary variables only

Normally when I do factor analysis, I have a whole bunch of variables that need to be reduced. But here I only have two binary variables (yes/no) that I need to reduce into one interval factor. Is ...
2
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1answer
234 views

Correspondence analysis on a table of means

I have a table of the following kind: Cat1 cat2 cat3 ... Var1 6.3 5.3 8.3 Var2 5.2 5.7 6.1 Var3 2.2 3.9 7.6 . . . It is a table of means for ...
2
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2answers
378 views

Calculate similarity between assortment of grocery shopping basket

I am trying to measure distances between basket assortments in a grocery shopping. I have all information that who buys what in every shopping by online and offline. I want to see the pattern of the ...
2
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1answer
2k views

Interpreting Canonical Correspondence Analysis (CCA) Inertia - in Vegan

I am wanting to know if I can use the ratio of Constrained/Total Inertia in my CCA to describe 'The variability explained by my constraining variables'. I am asking because I've seen different ...
2
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3answers
577 views

Which analysis for a set of (0/1)binary variables alone?

I have a dataset I would like to analyze and plot It consists of 100 binary variables (0/1) for about 2,000,000 observations There is absolutely no quantitative variable, nor anything I could use as ...
2
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1answer
181 views

How do I interpret the angles of two concentration ellipses?

Consider a map with two concentration ellipses like this below. The Vomit_y group is (almost?) perfectly vertical, while the Vomit_n group seems to be oriented at about 45 degrees. I understand that ...
2
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1answer
104 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 ...
2
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0answers
69 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 ...
2
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0answers
941 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 ...
2
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0answers
185 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, ...
2
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0answers
50 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 ...