not positive definite matrix :(

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Mar1an90
Posts: 3
Joined: Tue Jan 13, 2015 11:57 am

not positive definite matrix :(

Postby Mar1an90 » Tue Jan 13, 2015 12:05 pm

Hello,

I have run an factor analysis and a message about a 'not positive definite matrix' appeared instead of a desired correlation matrix. Field recommends to cry or try to figure out what's wrong with the data. What would be the next step to do?

Greetings and thanks for attention,

Mar1an90
GerineL
Moderator
Posts: 1477
Joined: Tue Jun 10, 2008 4:50 pm

Re: not positive definite matrix :(

Postby GerineL » Tue Jan 13, 2015 1:31 pm

Can you indicate what you have already tried and did not work?
For instance, No of participants might be too low (should be at least 3x no items) etc.
Mar1an90
Posts: 3
Joined: Tue Jan 13, 2015 11:57 am

Re: not positive definite matrix :(

Postby Mar1an90 » Tue Jan 13, 2015 3:27 pm

Thank you for your reply. Well, i have 30 variables and 147 respondents. I have not tried anything yet. The book of Field suggests to look out for very weak or very strong correlations, to drop some variables. But the message 'matrix is not positive definite' comes at the place in the output where the correlation matrix should be. So, I don't know what to do.

Greetings,

Mar1an90
GerineL
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Posts: 1477
Joined: Tue Jun 10, 2008 4:50 pm

Re: not positive definite matrix :(

Postby GerineL » Wed Jan 14, 2015 12:32 pm

try to run correlations through separate analysis (e.g., just correlate in analyze menu).
Mar1an90
Posts: 3
Joined: Tue Jan 13, 2015 11:57 am

Re: not positive definite matrix :(

Postby Mar1an90 » Wed Jan 14, 2015 1:52 pm

Oh, man, thank you very much. I feel very stupid now that I haven't considered this yet. I will try it and look if I can solve it. Have a nice day.
GerineL
Moderator
Posts: 1477
Joined: Tue Jun 10, 2008 4:50 pm

Re: not positive definite matrix :(

Postby GerineL » Thu Jan 15, 2015 12:19 pm

You're welcome, good luck!

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