-------- Original Message -------- Subject: MorphoJ - PLS: Blocks within a single configuration Date: Sun, 25 Sep 2011 19:26:24 -0400 From: Jana Makedonska <[email protected]> To: [email protected] Dear All, I am a relatively new MorphoJ user studying craniofacial integration. I used to apply a 2-block PLS approach to the study of the architecture of the cranium, yet I have realized that the relative orientation of units belonging to a functional whole should definitely be taken into account, and thankfully, Dr. Klingenberg has implemented such a test in MorphoJ. I have a question regarding the permutation tests of the singular axes in a PLS analysis within a single configuration. I am providing an example below: Overall strength of association between blocks: RV coefficient: 0.4261 Permutation test against the null hypothesis of independence Number of randomization rounds: 10000 P-value: <.0001 Singular values and pairwise correlations of PLS scores between blocks: Singular value P-value (perm.) % total covar. Correlation P-value (perm.) PLS1 0.00018668 1.0000 61.637 0.92015 <.0001 PLS2 0.00012496 1.0000 27.618 0.92618 <.0001 PLS3 0.00005060 1.0000 4.528 0.45438 0.8520 PLS4 0.00004219 1.0000 3.148 0.40476 0.8485 PLS5 0.00002855 1.0000 1.442 0.49857 0.1652 PLS6 0.00002183 1.0000 0.843 0.35042 0.6877 PLS7 0.00001383 1.0000 0.338 0.29619 0.7267 PLS8 0.00001321 1.0000 0.309 0.30962 0.3313 PLS9 0.00000881 1.0000 0.137 0.15853 0.8138 My question is: Why is the P-value of the singular axes always equal to 1? Also, why are the p-values of the singular axes and the correlations numerically identical when a 2-block PLS is run? (example pasted below) I do have the impression that when a 2-block PLS is run in one of the softwares of the IMP package, these p-values differed. Overall strength of association between blocks: RV coefficient: 0.1233 Permutation test against the null hypothesis of independence Number of randomization rounds: 10000 P-value: 0.0148 Singular values and pairwise correlations of PLS scores between blocks: Singular value P-value (perm.) % total covar. Correlation P-value (perm.) PLS1 0.00012760 0.0556 43.048 0.55104 0.0556 PLS2 0.00009617 0.0373 24.452 0.46313 0.0373 PLS3 0.00006845 0.1563 12.389 0.48423 0.1563 PLS4 0.00005697 0.0741 8.581 0.36577 0.0741 PLS5 0.00003937 0.3700 4.098 0.28668 0.3700 PLS6 0.00003259 0.2263 2.809 0.28990 0.2263 PLS7 0.00002723 0.1072 1.960 0.29277 0.1072 PLS8 0.00002195 0.0608 1.274 0.25144 0.0608 PLS9 0.00001644 0.0841 0.715 0.26427 0.0841 PLS10 0.00001275 0.0433 0.430 0.19014 0.0433 PLS11 0.00000960 0.0195 0.244 0.16680 0.0195 Any clue will be highly appreciated! Thanks! Jana ([email protected] <mailto:[email protected]>) -- -- "The world is full of mysteries. Life is one. The curious limitations of finite minds are another."(J.B.S. Haldane, The Causes of Evolution) Jana Makedonska, M.Sc. Ph.D. candidate/ Part-time lecturer Department of Anthropology College of Arts & Sciences State University of New York at Albany 1400 Washington Avenue 12222 Albany, NY Office phone: 518-442-4699
