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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24 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 ...
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0answers
33 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 ...
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1answer
30 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 ...
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0answers
15 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
33 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 ...
0
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0answers
36 views
When applying MDS, what can Eigenvalues tell about the input data?
Topic. Say, after applying MDS I collect all Eigenvalues:
case 1) there are 2 large positive and negative values outstanding from the crowd(-5,-3,3,5). the rest are large quantities of small, close ...
4
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2answers
127 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
27 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 ...
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1answer
101 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 ...
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0answers
61 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 ...
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0answers
109 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
20 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, ...
3
votes
0answers
25 views
Multidimensional scaling of random matrix
Suppose I have a random symmetric matrix W of size $n\times n$, with i.i.d. coefficients uniformly distributed in [0,1], and I set $W_{ii} = 0$.
Then I apply a Multidimensional Scaling of dimension ...
2
votes
1answer
52 views
Individual differences scaling, additional investigations
I am learning individual differences scaling (AKA three-way multidimensional scaling) and I want to know what different ways there are to state that my results are reliable.
I had to perform ...
1
vote
0answers
39 views
Sequential or dynamic multidimensional scaling
I am looking for a way to conduct sequential (dynamic) MDS based on several variables coded for a sequence of stimuli. Could anyone direct me to software for this purpose (especially R packages / ...
2
votes
0answers
191 views
Normalizing data before applying MDS with strain criterion
The features of my dataset are like below:
• BI-RADS assessment: 1 to 5 (ordinal)
• Age: patient's age in years (integer) ...
1
vote
1answer
64 views
Is first dimension more informative in multidimensional scaling?
A property of Principal Components Analysis (PCA) is that the first dimension is the most informative, next the second and so on. Is this property true also for multidimensional scaling (MDS)?
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109 views
Non-metric multidimensional scaling with dichotomous independent variables?
I have a set of t-rflp fragment-length profiles from an investigation into microbial degradation of hydrocarbons as part of my undergrad dissertation. I want to study the effect of various variables ...
8
votes
1answer
1k views
RandomForest - MDS plot interpretation
I used randomForest to classify 6 animal behaviours (eg. Standing, Walking, Swimming etc.) based on 8 variables (different body postures and movement).
The MDSplot in the randomForest package gives ...
1
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0answers
37 views
Computing and comparing semantic networks generated by grouped individuals
I have 2 groups, each containing 20 individuals. For each individual I have a dissimilarity matrix of a number of judged items. I'd like to evaluate whether there is an overall difference between the ...
1
vote
3answers
198 views
Metric and Clustering Method
I need some suggestions regarding what kind of metric and clustering analysis I should use. I read a lot of posts but didn't get any hints about this type of data.
I have a 3000*5000 matrix, where ...
0
votes
1answer
81 views
Is a Biplot suitable ? Domestic Violence VS Non-Violence data
I have a small data set that consists solely of counts. I have several variables. For example State, for each state (Mexican States), for example, Tamauplipas I have the counts of domestic violence ...
0
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1answer
87 views
Methods of “Two-Way” Multidimensional Scaling (MDS)?
I just want to ask about the MDS. Below is the subcategory of the Multidimensional Scaling topic.
Multidimensional Scaling
Metric and Non-Metric Models
Methods of "Two-Way" Multidimensional Scaling ...
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2answers
404 views
What is the role of MDS in modern statistics?
I recently came across multidimensional scaling. I am trying to understand this tool better and its role in modern statistics. So here are a few guiding questions:
Which questions does it answer?
...
3
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0answers
168 views
Quantifying differences in a discrete distribution across several populations
Suppose you have a discrete random variable, $Y$, with a large number (say, $300$) of discrete (which happen to be nominal) possible outcomes. The mass function, $p(y)=P(Y=y)$, is unknown but a sample ...
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1answer
902 views
How can I calculate the R-square value of an MDS to assess the fit of the model to the data in R?
I would like to do Multidimensional Scaling (MDS) using cmdscale() in R. I have read that it is useful to try out how many dimensions are suitable for the data by ...
33
votes
4answers
6k views
What's the difference between principal components analysis and multidimensional scaling?
How are PCA and classical MDS different? How about MDS versus nonmetric-MDS? Is there a time when you would prefer one over the other? How do the interpretations differ?
4
votes
1answer
908 views
Interpretation of MDS factor plot
Suppose I run Multidimensional Scaling and I got the resulting plot. Can anybody suggest me how to interpret the plot. Please find one of my result below. Here I've 5 concepts which I run the MDS ...
5
votes
2answers
609 views
Visualizing multi-dimensional data (LSI) in 2D
I'm using latent semantic indexing to find similarities between documents (thanks, JMS!)
After dimension reduction, I've tried k-means clustering to group the documents into clusters, which works ...
5
votes
2answers
264 views
Big-O Scaling of R's cmdscale()
I'm trying to run R's multidimensional scaling algorithm, cmdscale, on roughly 2,200 variables, i.e. a 2,200x2,200 distance matrix. It's taking forever (about a ...
5
votes
2answers
1k views
Multidimensional scaling pseudo-code
I am planning to write a program that performs MDS. Any pointers to where I can access the pseudo-code for MDS?
Thanks!
5
votes
1answer
3k views
Data normalization and standardization in neural networks
I am trying to predict the outcome of a complex system using neural networks (ANN's). The outcome (dependent) values range between 0 and 10,000. The different input variables have different ranges. ...
2
votes
1answer
1k views
Adding labels to points using mds and scatter3d package with R
I have a dataset forwhich i have performed an mds and visualized the results using scatterplot3d library. However i would like to see the names of the points on the 3d plot. How do i accomplish that? ...
3
votes
1answer
458 views
Help me understand nMDS algorithm
I have been reading Zuur, Ieno and Smith (2007) Analyzing ecological data, and on page 262, they try to explain how nMDS (non-metric multidimensional scaling) algorithm works. As my background is in ...
