5k 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 ...
889 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 ...
794 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 ...
983 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?
348 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 ...
325 views

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 ...
173 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, ...
116 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 ...
107 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 ...
61 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 ...
70 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 ...
50 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 ...
43 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 ...
After an eigenvector computation for PCA, I get the eigenvector $(a, b)$ where $a=b$. This means that if I choose $a=1$, then also $b$ would be equal to $1$, and if I choose $a=2$, $b$ would also be ...