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In praise of progress

Posted by GedR on 20 Jul 2012 at 17:31 GMT

Similar points have been made on the FreeSurfer mailing list already, but I think it's worth repeating here: results should be expected to change significantly when new major revisions of software are released -- otherwise, how can developers ever make improvements?

Similarly, segmentations by expert neuroradiologists should be expected to change when new improved manual tracing protocols are developed.

Differences between HP and Mac, or between Mac versions are more worrying, but note that the article says:

"for the volumes, significant differences were derived only for the cross-version contrasts v5.0.0 vs. the two earlier versions"

"in case of the HP vs. Mac and Mac OSX 10.6 vs. OSX 10.5 contrasts, significant CT differences were found for versions v4.3.1 and v4.5.0, whereas no significant CT differences were present at all for version v5.0.0."

My reading of this is that for the latest version of FreeSurfer tested here, there are no statistically significant differences in either volume or cortical thickness due to Mac/HP or OSX10.5/6 -- another form of progress!

Competing interests declared: I have previously made changes to the SPM software that can change (improve, I hope!) results between versions, e.g.
http://www.ncbi.nlm.nih.gov/pubmed/22037420