Re: Correlation matrix is not positive definite

Posted by Art Kendall on Nov 17, 2011; 12:21pm
URL: http://spssx-discussion.165.s1.nabble.com/Correlation-matrix-is-not-positive-definite-tp4999980p5001017.html

That is definitely the situation. Whenever you have more variables than cases, variables are perfectly predictable from each other.

Please describe your data in more detail.
How did you choose these cases?
Each is ___________.
What are the groups of cases?
It looks like some kind of repeated measures data. The measures appear to be iterated by wave length similar to the way time series data is iterated by time. Is this correct?
the wavelengths run from 250 to 430 somethings.  Somethings measure________.
Are all wavelengths 1 something apart?
Are these ipsative/compositional data? I.e., do they sum to a constant?
What is the purpose of your research?  What is the phenomenon your are interested in?  What do you want the data to tell you?

With this information list members are more likely to be able to make suggestions about approaches and/or places to post your query.


Art Kendall
Social Research Consultants

On 11/16/2011 11:25 PM, viswa21 wrote:

Dear all,
I am new to SPSS software. Trying to obtain principal component analysis
using factor analysis. The correlation matrix is giving a warning that it is
"not a positive definite and determinant is 0".

Please take a look at the xlsx file. The data is about fluorescence emission
spectrum of bacteria. Variables are wavelength of excitation.
<a class="moz-txt-link-freetext" href="http://">http:// http://ifile.it/9lvg18d/3%20bacteria.xlsx


The data contains more variables than cases. I don't know whether is this
causing the problem. I can not see KMO-Bartletts parameter even though i
selected it in descriptive.

Reducing the variables solve this problem?? Any help would be invaluable to
me. Thanks a million!!

Visu

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