Monday, March 5, 2012


cc:, "Myles Allen" <>, "Eduardo Zorita" <>,,,,,
date: Thu, 2 Nov 2006 09:38:00 -0000 (GMT)
from: "Tim Osborn" <>
subject: Re: CPD submission
to: "Martin Juckes" <>

On Thu, November 2, 2006 8:41 am, Martin Juckes wrote:
> Please respond to this point: a principal component of centred data has
> zero
> mean.


yes, this point is mathematically correct. Each PC time series is a
weighted mean of the time series at each point in the field, and if each
of those has zero mean, then of course each PC will have zero mean. I
agree. So I don't expect McIntyre to argue against this basic point. But
I complained publicly that MM03 should have been sent to MBH for comment
before it was published, in case MBH had simple explanations for some of
the complaints made in MM03. Which is why I now suggested that you
question McIntyre prior to posting it publicly on CPD. Yes it is a basic
point, but it would be good to know what his response might be in advance
of posting it publicly, so that you can make sure that the way you have
worded the posting already deals with any obfuscation that he might later
attempt. You don't need to mention that you will be posting a comment on
this; it is sufficient to say that, now you have his code, you have looked
into it and it does not seem to centre the data prior to the PCA, and this
is contrary to... etc. and can he clarify the matter.

Regarding the CPD posts, it might be simplest to post 3 separate pieces:
(1) providing the update with regards code availability, which I guess we
can all sign; (2) discussing data/code availability; and (3) after getting
a response from McIntyre, pointing out the centering problem with his
code/results, which some of us might sign depending on McIntyre's
response. By splitting them this way, there is no need to wait for (3)
before posting (1) and (2).

Presumably the manuscript itself will be changed after the
review/discussion phase, but for now we just leave it as submitted and
post these comments separately? I wonder if McIntyre will complain that
the manuscript itself will retain the complaint about code unavailability
until the revision phase?



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