# Questions tagged [parallel-analysis]

Parallel analysis is a criterion used to help decide the number of principal components or principal factors/common factors to retain. It is based on retaining eigenvalues of observed data greater than those corresponding mean eigenvalues from many data sets of uncorrelated data with the same $n$ observations and $p$ variables as the observed data.

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### Squared Multiple Correlation (SMC) of my correlation matrix tend towards 1. How to interpret this?

In order to be able to conduct exploratory factor analysis, I want to carry out parallel analysis to determine the number of factors to be extracted. To do so, I want to extract the eignevalues of the ...
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### What statistical techniques can I use to model improvement over time?

Say you have a group of 30 students and you measure each individual's performance on a test at 4 intervals throughout the year. (For the purpose of this investigation, assume the tests taken are ...
555 views

### Unexpected eigenvalues in parallel analysis for factor analysis in SPSS

Would greatly appreciate if someone could clarify which eigenvalues I am supposed to compare when using parallel analysis to determine factor retention. I am running Principal Axis Factoring in SPSS ...
579 views

### Choosing how many factors to retain based on parallel analysis and on a scree plot without an elbow

When I realize the Factor Analysis (I have 16 items), the PCA says I have 5 factors. But in the scree plot there is no elbow at all, just a decreasing line, that makes me think maybe I shouldn't be ...
311 views

### How do random data eigenvalues change, as random variables are added?

I am using parallel analysis (Horn 1965) to determine how many principal components I can extract from my data. I can add more variables to my dataset, but I cannot add more cases (I know, that's ...
1k views

### Strange results in parallel analysis — weird output by rstudio but not R-Fiddle

Major UPDATE based on discussion with Aleksandr Blekh's answer (thanks so much!): This MRE would run with no problem in R-Fiddle ...
11k views

### How to correctly interpret a parallel analysis in exploratory factor analysis?

Some scientific papers report results of parallel analysis of principal axis factor analysis in a way inconsistent with my understanding of the methodology. What am I missing? Am I wrong or are they. ...
583 views

### Permutation test for factor analysis

We have a survey instrument and are interested in assessing dimensionality of it. Looking at plots of multidimensional scaling, it appears as though there are, perhaps, 3 distinct dimensions to the ...
2k views

### Can I do parallel analysis with any type of exploratory factor analysis/principal component analysis?

I wish to perform parallel analysis to determine how many factors I should extract from my maximum likelihood exploratory factor analysis. I have been referred to a program that calculates the ...