Technique that renders observed or computed (dis)similarities among objects into distances in a low-dimensional space (usually Euclidean). It thus constructs dimensions for the data; the objects can be plotted and conceptualized in those dimensions

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2
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14 views

Using the results of a non-metric multidimensional scaling to derive a measure of deviance

I'm working with a dataset containing the taxonomic compositions of floras all over the world and performed a non-metric multidimensional scaling (NMDS) based on the relative proportions of plant ...
0
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0answers
7 views

Multidimensional Scaling - external scale regression using standardized or unstandardized weights

I am having trouble determining whether to use standardized or raw regression weights when using multiple regression to interpret Multidimensional Scaling plots. Different textbooks seem to advocate ...
1
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1answer
35 views

Normalizing Vs. Scaling

Are the concepts of normalizing and scaling of data in conflict with each other? I am adding weights to my features, I have tried normalizing the weights and it didn't make any difference in the ...
0
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1answer
12 views

should weights be scaled too?

I am using supervised learning algorithms (specificly SVM) on my data. I know that scaling was needed for my input data. however as I am also adding weights (using pairwise comparison), I am not sure ...
0
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1answer
24 views

How to : a brief intro to scaling and rescaling data ( inputs) for supervised learning algorithms

I understand the concept of scaling and that it improves results in SVM's and NN's. however I would like to find somewhere where is is explained, in easy "layman's terms" terms. of how it is done. I ...
1
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1answer
22 views

Scaling in SVM (why and how to , plus references)

Hi I know why feature scaling is preferred in SVM, I have two questions: 1-does anyone know of legit articles of books explaining it. I am writing my thesis and I need references. It doesnt have to be ...
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0answers
18 views

Rotation of Mean Centred Variables in Principle Components Analysis

I'm looking to manually (Excel) perform PCA without any statistical packages such as R, but having trouble understanding how to rotate the original variables to find the maximum variance for the new ...
0
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0answers
16 views

Is subtracting the mean from PCA necessary when using an SVD result that is feature scaled?

I've applied SVD to the original data matrix and eliminated insignificant columns and rows from U and V^T respectively using the Sigma values. I multiplied together my optimized U, Sigma, and V^T ...
1
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1answer
30 views

Is it posible to perform the inverse of multidimensional scaling analysis

We have lot of 3D data and we reduced it to 2D for performing fuzzy clustering and obtaining prototypes. We used some matlab functions that were very well documented. Now we would like to see to which ...
4
votes
1answer
121 views

How to distance and to MDS-plot objects according their complex shape

Suppose I have four basal forms of signal (blue, purple, red, green). I also have created transition forms between each other. If you carefully look on the picture below, you can see that for example ...
1
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0answers
18 views

Suitable plot for 5 dimensional feature vectors?

I have a list of personality scores obtained from 100 people, based on the Big-Five personality test. Each person has one score for each of the five assessed traits. I put these scores into a 5 ...
0
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0answers
20 views

Converting data from classical scaling in MDS

I implemented the classical scaling and obtained the relative coordinates in Java. I want to translate these relative positions, but I am not getting how I should be doing this. This is just like: ...
0
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0answers
39 views

Is it correct to combine PCA and NMDS axes in a multiple regression?

I am considering to do a multiple regression in which some of the predictive variables are PCA (principal components) axes whereas others are NMDS (nonmetric muliple dimension scaling) axes. I would ...
2
votes
1answer
82 views

Multidimensional Scaling “eurodist”

I have a question regarding Multidimensional Scaling. I used the dataset eurodist from the package datasets to generate a 2 ...
0
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0answers
68 views

Draw biplot on nonclassical MDS interpration?

How can I draw similar biplot like you can on PCA, so I could compare these two visualization techniques / methods? I got dissimilarities and distances of my data in simple plot, but I would like it ...
0
votes
1answer
261 views

Multidimensional scaling using Python

I have 6,000 points for which I have all pairwise distances in a distance matrix. I want to get an idea whether these data were generated by a mixture of Gaussian distributions so I'm trying to get a ...
0
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0answers
113 views

What exactly is the vector fitting on a nMDS plot telling me about community structure?

I think I have a basic misunderstanding of what the vectors typically plotted over an nMDS (non Metric Multidimensional Scaling) plot are telling me. I understand the direction of the vectors point to ...
0
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0answers
39 views

How to de-trend the data before doing MDS?

I am given a set of regions' macro-economical development indices, such as number of unemployed, gross value added, and so on. Each index naturally is correlated with a size of the region. I want to ...
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0answers
26 views

Multidimensional scaling of variables with multiple sub-features?

Let's say I have a year's worth of magazine issues (January, February, March, etc), and I want to visualize the differences among them. The classic example of multidimensional scaling (MDS) would have ...
0
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0answers
45 views

Scaling data in machine learning algorithm

I am currently working on a linear classifier, which uses the statistical learning paradigm; that is, no knowledge about the distribution from which that training data are drawn from is available. ...
1
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0answers
41 views

Steps to follow for correspondence analysis when each brand is not shown to every respondent

I want to understand the steps followed for correspondence analysis when each brand is not shown to every respondent. Till now I used to assign a number (proportion) to each brand for each attribute ...
1
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1answer
218 views

Guttman's smallest space analysis

I am trying to replicate an analysis as conducted by Raven, et al. (1998). A scale is analyzed with Guttman's smallest space analysis. First of all I wasn't able to find a suitable procedure in R and ...
1
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1answer
111 views

Kernel PCA with an SVD algo

Suppose that I have a great algo for calculating the SVD and I want to do Kernel PCA. It is possible to first apply the Kernel function to my data and then run the SVD algo on the transformed data?
1
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1answer
65 views

Multidimensional quantiles

I have 1000 observations with 2 continuous variables : Observation ID | X | Y
1
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0answers
144 views

Gower distance and MDS: How to determine which variables count?

I have morphological data from two different determined groups (It and Nd), where the variables are heterogeneous (continuous, ...
1
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0answers
79 views

When using Nonmetric Multidimensional Scaling, is there an explanatory metric similar to loadings in PCA?

As a beginner to MDS, here is my thought process: Given a data set of environmental factors that may effect a certain sites, when I run a PCA on each site I get a list of principal components. If I ...
0
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0answers
255 views

Multidimensional scaling in R with Spearman's rank correlation

I'm new to MDS, but I found some good starter code here (http://mhermans.net/static/postdata/r-examples/neighbours-mds/neighbours-mds-example.html) and which I borrowed for below. The code works fine, ...
3
votes
2answers
341 views

Perform feature normalization before or within model validation?

A common good practice in Machine Learning is to do feature normalization or data standardization of the predictor variables, that's it, center the data substracting the mean and normalize it dividing ...
0
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1answer
63 views

Multidimensional scaling for big dissimilarity matrix

I have a large symmetrical dissimilarity matrix of dimension 300 000. Can you please suggest the multidimensional scaling algorithms that can work with such large data? Input of course can be the ...
1
vote
1answer
56 views

Which values to use for scaling out of sample PCA data

I have centered and scaled inputs via prcomp (): prOut<-prcomp(trainSet[,2:4],scale = TRUE,scores=TRUE) I now want to use ...
0
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0answers
48 views

Transforming distance matrix to univariate data

Is there a valid mathematical or statistical approach to converting site by site distance objects/matrices to a univariate site vector or column in a dataframe? I have a Euclidean distance matrix for ...
2
votes
0answers
103 views

Why does some model-based clustering fail to fit with a large number of dimensions?

I am attempting to cluster data using Mclust. The data is originally from a dissimilarity matrix, transformed via multidimensional scaling in R (MASS::isoMDS). As I ...
2
votes
0answers
147 views

whether to rescale indicator / binary / dummy predictors for LASSO

For the LASSO (and other model selecting procedures) it is crucial to rescale the predictors. The general recommendation I follow is simply to use a 0 mean, 1 standard deviation normalization for ...
0
votes
1answer
150 views

Analysing data measured as proportional composition

I have a data set on the proportional composition of marine substrate for different locations which I would like to compare. For example, one replicate transect within a location may be 50% sand, 25% ...
2
votes
0answers
290 views

How to interpret variation explained by principal coordinates?

I have recently seen a couple of Principal Coordinates Analysis (PCoA) projection plots which show "percentage variation explained" by the respective principal coordinates. Given that the analysis is ...
1
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0answers
23 views

Issue of multiple scaling method

I plan to use multiple scaling in R and start with a toy example. There are two matrices. The first contains 10 observations and the second one contains two replicated rows. It appears that the ...
2
votes
0answers
24 views

How to enhance the performance of naive CMDS?

I'm performing Classical MDS on the distance over columns of binary matrix. The result is like this: The points lies on two lines vertical to each other. I don't think useful information is shown ...
8
votes
3answers
265 views

How to project high dimensional space into a two-dimensional plane?

I have a set of data points in a N-dimensional space. In addition, I also have a centroid in this same N-dimensional space. Are there any approaches that can allow me to project these data points into ...
3
votes
1answer
261 views

MDS and PCA eigenvalues and eigenvectors

I understand that Multidimensional scaling (MDS) is same as doing Principal Components analysis (PCA) if Euclidean distance is used, this is known as Metric MDS. But I came across this in a book that ...
0
votes
0answers
63 views

Multidimensional scaling

I am running into some problems performing a multidimensional scaling image. First of my dataset is quite large (330.000 fields: 33000 rows, 10 columns). The output image needs to contain 10 dots, 1 ...
0
votes
1answer
105 views

NMDS: why is the r-squared for a factor variable so low

I am doing an NMDS ordination. The data come from a number of sites scattered around two lakes. In the plots, I coloured the samples from the two lakes blue and green. There seems to be some pretty ...
2
votes
1answer
350 views

NMDS and variance explained by vector fitting

I just ran a non metric multidimensional scaling model (nmds) which compared multiple locations based on benthic invertebrate species composition. After running the analysis, I used the vector fitting ...
-1
votes
1answer
86 views

NMDS for biomass

I would like to make a NMDS with biomass of different prey groups in stomach content of fish. I have already made one where the data matrix consists of 0 and 1, and this one went fine but are not ...
1
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0answers
147 views

R - Multidimensional Scaling and Missing Values

I include MDS analysis in a customer survey and have about 10 brands I want to include in the perceptual map at the end. Meaning the customers would have to rate 45 comparisons and give a similarity ...
4
votes
2answers
575 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 ...
1
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0answers
55 views

The proper scaling for generating uniformly distributed points in the n-d ball of *non-unit* radius?

The question of generating uniformly distributed points on the surface of n-dimensional unit ball has been already posted here a dozen of times. What I'm interested in is the proper scaling when we ...
0
votes
1answer
153 views

How to scale new datas when a training set already exists

Here is what I have : A scaled training set, with labels. Segmented images, from which I extract new vectors to classify. My classifier is a KNN which would have obviously been trained using my ...
0
votes
1answer
150 views

Finding the projection used in multidimensional scaling

Background I have a set of data points in high-dimensional (512D) space that I wish to map to 2D for visualisation. I am interested in observing in 2D the (approximate) relative distances between the ...
0
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0answers
331 views

Multidimensional scaling on distance or similarity matrix

Why doesn't the scatter plot change when I perform multidimensional scaling on distance or similarity matrix? This figure uses similarity matrix And this figure use distance matrix ...
1
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0answers
32 views

Separate points in 3 or more dimentions into 2 groups with labels A and B

How can you separate a group of points in 3 dimensions into two groups with labels A and B? My approach: If we draw a plane through the cloud of points, the group A can be the points above the plane, ...