I am a novice to PCA, and was wondering if there were any other ways other than those specified in the tutorial of retaining factors in the EP toolkit?
For example, I would like to try to retain factors using the minimum percentage of total variance explained by each factor as the criterion, rather than the "Minimum %age accounted for criterion" visible in the scree plot graphic window (which I assume means the minimum percentage of total variance accounted for by all would-be retained factors together). I understand you can access this information in the 'Edit > Factors' tab, but that only allows me to see the contributions of individual factors after running the factor solution, so I would like to know if you can access this kind of information before running a factor solution? Or perhaps there is a way to change the scale of the y-axis of the scree plot to percentage of total variance explained to at least see this information in the scree plot graphic?
Thanks in advance,
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Not currently I'm afraid. Revisiting the factor retention process is definitely on my todo list but it will be awhile I'm afraid. I've got a lot of other things to tackle first.
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If anyone else has this problem I got the info I wanted by calculating the covariance matrix in matlab using 'conv', then running the eigen decomposition using 'eig', and then scaled the eigenvalues to percentage variance accounted for by dividing each eigenvalue by the sum of all eigenvalues and multiplying by 100. The results were identical to those in the EP toolkit screeplot when you select number factors = 0.
Regards,
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Hello,
I am a novice to PCA, and was wondering if there were any other ways other than those specified in the tutorial of retaining factors in the EP toolkit?
For example, I would like to try to retain factors using the minimum percentage of total variance explained by each factor as the criterion, rather than the "Minimum %age accounted for criterion" visible in the scree plot graphic window (which I assume means the minimum percentage of total variance accounted for by all would-be retained factors together). I understand you can access this information in the 'Edit > Factors' tab, but that only allows me to see the contributions of individual factors after running the factor solution, so I would like to know if you can access this kind of information before running a factor solution? Or perhaps there is a way to change the scale of the y-axis of the scree plot to percentage of total variance explained to at least see this information in the scree plot graphic?
Thanks in advance,
Not currently I'm afraid. Revisiting the factor retention process is definitely on my todo list but it will be awhile I'm afraid. I've got a lot of other things to tackle first.
Hello,
OK, I look forward to it, thanks for your help!
Regards,
If anyone else has this problem I got the info I wanted by calculating the covariance matrix in matlab using 'conv', then running the eigen decomposition using 'eig', and then scaled the eigenvalues to percentage variance accounted for by dividing each eigenvalue by the sum of all eigenvalues and multiplying by 100. The results were identical to those in the EP toolkit screeplot when you select number factors = 0.
Regards,