Linked Questions

10
votes
4answers
7k views

Is it acceptable to reverse a sign of a principal component score? [duplicate]

I have two datasets from similar psycholinguistic experiments. In both of them, information about the participant's reading and spelling ability was collected, then converted into standardized scores ...
1
vote
1answer
2k views

Reverse the sign of PCA [duplicate]

I'm struggling on getting a good explanation for the unexpected signs of Principal Component for months. I tried to replicate a result and I got exactly the opposite signs for all components. While I ...
2
votes
2answers
1k views

How does pca() function in Matlab fix the sign of principal components? [duplicate]

PCA gives me loadings with different signs. I understand that I may simply revert them (as explained in this thread), but I need an explanation (my boss insists) of why Matlab implementation gives me ...
4
votes
1answer
1k views

Is the sign of principal components meaningless? [duplicate]

Does the sign of the vectors returned by PCA have any significance after I center my variables?
0
votes
0answers
2k views

EFA: interpreting negative factor loadings [duplicate]

I've run an exploratory factor analysis with oblique rotation, and specifying three factors. The first two factors are correlated at almost zero with one another, while there's a negative correlation ...
1
vote
0answers
361 views

Is it possible to reverse the sign of factor loadings for one factor? [duplicate]

I just want to confirm if it is possible to reverse the sign (+/-) on the factor loadings of one factor. I run a PAF with Oblimin rotation. I obtained 6 factors but in one of them the items that load ...
0
votes
1answer
183 views

PCA scores in my own implementation have different sign from the ones computed in R [duplicate]

I am trying to implement PCA (NIPALS method) using Excel. The problem is that my results are not exactly matching with the results of R. There is only a difference in sign: if my scores are positive, ...
0
votes
0answers
191 views

Does it mean anything when all items load negatively on one factor? [duplicate]

note: A few people have marked this question as duplicate - But my question here is not answered in the other question. Though a fine distinction, what I was asking about here was not whether the ...
1
vote
0answers
125 views

How to reverse the sign of factor loadings in factor analysis? [duplicate]

I'm doing a factor analysis and using the resulting factors in a regression. I'm using SAS. A number of the variables load positively on a factor. In order to make it easier to interpret in the final ...
0
votes
1answer
95 views

What does it mean to have a high/low value for a sample in the 1st principal component? [duplicate]

I applied PCA on an $n\times p$ matrix where $n$ means the number of samples and $p$ means the number of variables, and I am using the 1st principal component (PC) as the new representation of the ...
1
vote
0answers
75 views

Getting PCA eigenvectors with the values of opposite sign [duplicate]

I am performing a PCA analysis in Matlab on a $110\times 7$ dataset using some custom code. I am checking my code against Matlab's princomp and my eigenvectors are ...
0
votes
0answers
52 views

Principal Component Analysis [duplicate]

I am doing PCA using Matlab's pca() function and R's prcomp() function. They give identical principal components in some cases and same values and opposite sign in some other cases. Why is this ...
1
vote
0answers
48 views

Eigenvectors computed by Matlab's princomp() and eig() have different signs [duplicate]

I am trying to write a PCA function in MATLAB. I know that there is the function princomp, I just wanted to understand the process for myself. One problem I've ...
1
vote
0answers
38 views

Why are the directions of eigenvectors in SVD and Eigen-Decomposition for PCA opposite? [duplicate]

As you may know, scikit-learn library utilizes singular value decomposition (SVD) of data matrix X to produce eigenvectors for PCA. I decided to code PCA by using ...
0
votes
1answer
29 views

Different tools for calculating PCA [duplicate]

I have a test csv file and I have written a code via Scikit to show the PCA for that. I also use another tool in Excel (XLSTAT) to compare the results. The XLSTAT automatically calculates the number ...

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