Dear SPM experts,
Your advice would be appreciated on the following. I’m running into some trouble with a 2-way repeated-measures ANOVA in SPM12. I have 48 subjects and 2 within-subjects factors, factor A with 2 levels and factor B with 4 levels. I have created 8 contrast maps per subject at first level, each of which represents one of the 2x4 unique factor combinations. This means I have 8*48 = 384 scans as data in my GLM.
I’ve specified a flexible factorial 2nd-level GLM as follows:
- Factor 1: name ‘A’, dependent YES, variance EQUAL
- Factor 2: name ‘B’, dependent YES, variance EQUAL
- Factor 3: name ‘subject’, dependent NO, variance EQUAL
- Each subject is added separately, with:
o Scans: the 8 contrast maps in order A1B1-A2B1-A1B2-etc
o Conds: [1,1;2,1;1,2;2,2;1,3;2,3;1,4;2,4]
- Main effect for factor 1 (A): 1
- Main effect for factor 2 (B): 2
- Main effect for factor 3 (subject): 3
- Interaction effect for factors 1 and 2: [1,2]
When I attempt to estimate this model, SPM crashes after about 5 or 6 steps of the ReML estimation algorithm. Error message: ‘The requested tolerance is too high.’ Find the entire error stack below.
I’ve searched this mailing list and consulted the very helpful tutorial by Glaescher & Gitelman (2008) (http://www.sbirc.ed.ac.uk/cyril/download/contrast_weighting_glascher_gitelman_2008.pdf), but can’t figure out what I did wrong. I played around with the order of the factors, putting ‘subject’ first (G&G mention this), flipping the order of factors A and B, etc, but SPM still crashed.
The error message makes me think that I could solve the problem by raising the tolerance of the GLM estimation algorithm somehow, but I’m not sure if that would violate any good practice, and I wouldn’t know how to go about it either.
Did I specify my model correctly? Have you encountered this error before, what might it mean, and how can I solve it?
Thank you very much.
Best regards,
Jeroen van Baar
PhD student @ Donders Institute, Nijmegen, The Netherlands
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SPM12: spm_est_non_sphericity (v6913) 16:21:57 - 23/01/2018
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Chunk 1/1 : ...done
Temporal non-sphericity (9079 voxels) : ...ReML estimation
ReML Iteration 1 : ...4.053974e+02 [+4.25]
ReML Iteration 1 : ...4.052294e+02 [+4.75]
ReML Iteration 1 : ...4.049247e+02 [+5.25]
ReML Iteration 1 : ...4.043815e+02 [+5.75]
ReML Iteration 1 : ...4.032816e+02 [+6.25]
ReML Iteration 1 : ...4.010746e+02 [+6.75]
ReML Iteration 1 : ...3.968957e+02 [+7.25]
Failed 'Model estimation'
Error using spm_dx>expv (line 279)
The requested tolerance is too high.
In file "/home/common/matlab/spm12/spm_dx.m" (v7144), function "expv" at line 279.
In file "/home/common/matlab/spm12/spm_dx.m" (v7144), function "spm_dx" at line 102.
In file "/home/common/matlab/spm12/spm_reml.m" (v7178), function "spm_reml" at line 145.
In file "/home/common/matlab/spm12/spm_reml.m" (v7178), function "spm_reml" at line 160.
In file "/home/common/matlab/spm12/spm_reml.m" (v7178), function "spm_reml" at line 160.
In file "/home/common/matlab/spm12/spm_reml.m" (v7178), function "spm_reml" at line 160.
In file "/home/common/matlab/spm12/spm_reml.m" (v7178), function "spm_reml" at line 160.
In file "/home/common/matlab/spm12/spm_reml.m" (v7178), function "spm_reml" at line 160.
In file "/home/common/matlab/spm12/spm_reml.m" (v7178), function "spm_reml" at line 160.
In file "/home/common/matlab/spm12/spm_est_non_sphericity.m" (v6913), function "spm_est_non_sphericity" at line 281.
In file "/home/common/matlab/spm12/spm_spm.m" (v7120), function "spm_spm" at line 433.
In file "/home/common/matlab/spm12_r6470_20150506/config/spm_run_fmri_est.m" (v7057), function "spm_run_fmri_est" at line 34.
The following modules did not run:
Failed: Model estimation
Error using MATLABbatch system
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