Just for reference: here’s the code excerpt where Mann calculates the cross-validation R2 statistics and then writes it to file. You can see the original code at ftp://holocene.evsc.virginia.edu/pub/MANNETAL98/METHODS/multiproxy.f.{Update –
http://www.meteo.psu.edu/holocene/public_html/shared/research/MANNETAL98/METHODS/multiproxy.f
] Search down using corrnhem or verif1,out. There is no "if" as to whether he calculated the cross-validation R2 statistic.
The following Fortran code calculates the cross-validation R2 statistics for global (corrglob**2) and NH (corrnhem**2) and then saves these results to the file verif1.out. The Fortran code is very pedantic for a simple operation, but you should be able to see what’s going on. (I’m old enough that I actually learned Fortran when I was young; I never imagined that anyone would still be using it.)
amean1 = zero
amean2 = zero
amean3 = zero
amean4 = zero
varverglob = zero
varvernhem = zero
varcalglob = zero
varcalnhem = zero
corrglob = zero
corrnhem = zero
do iy=iymin,iymax
amean1 = amean1+globv(iy)
amean2 = amean2+nhemv(iy)
amean3 = amean3+globc(iy)
amean4 = amean4+nhemc(iy)
end
do amean1 = amean1/float(iymax-iymin+1)
amean2 = amean2/float(iymax-iymin+1)
amean3 = amean3/float(iymax-iymin+1)
amean4 = amean4/float(iymax-iymin+1)
do iy=iymin,iymax
varcalglob = varcalglob + (globc(iy)-amean3)**2
varcalnhem = varcalnhem + (nhemc(iy)-amean4)**2
varverglob = varverglob + (globv(iy)-amean1)**2
varvernhem = varvernhem + (nhemv(iy)-amean2)**2
corrglob = corrglob + (globv(iy)-amean1) $ *(globc(iy)-amean3)
corrnhem = corrnhem + (nhemv(iy)-amean2) $ *(nhemc(iy)-amean4)
end do
corrglob = corrglob/sqrt(varverglob*varcalglob)
corrnhem = corrnhem/sqrt(varvernhem*varcalnhem)
Later on…
open (unit=9,file=’corrs-verif1.out’,status=’unknown’)
write (9,*) ‘globe: ‘,corrglob,corrglob**2
write (9,*) ‘nhem: ‘,corrnhem,corrnhem**2
8 Comments
Dear Senator Barton,
In answer to your question:
My answer is:
Sincerely
Dr Michael Mann
University of Virginia
If it is true that McIntyre and McKitrick’s results are “without statistical and climatological merit” as Mann argues, and it is also true that McIntyre and McKitrick results have duplicated Mann’s results using the same data sets and same methods, then it logically follows that Mann et al.’s results are “without statistical and climatogical merit.”
The logical conclusion seems to be that Mann’s reconstruction should be withdrawn and ignored and any other study that used bristlecone pines or other dubious time series should also be withdrawn. As far as I can tell this would leave only Moberg’s study and an earlier one by Hu (1997) using borehole data as potentially valid reconstructions. Both of these reconstructions show the MWP and LIA, great natural variability of climate, and a warming commencing around 1600 that has continued into the present.
Steve: I do get a little weary of them attributing our emulation of MBH98 results without bristlecones as “our” reconstruction. Howver, re-stated in this way (which is useful), they have in effect said (And all parties agree) that an MBH98 reconstruction without bristlecones is “without statistical and climatological merit”. They claim that a reconstruction with bristlecones, on the other hand, has unique statistical and climatological merit, even if the bristlecones are contaminated with CO2 fertilization. The short discussion in MBH99 is bait-and-switch. They raise the issue of CO2 fertilization, but ddo not adjust any MBH98 results, but suggest to readers now that they did. The CO2 adjustment in MBH99 is bogus – it adjusts 19th century values and argues that the CO2 fertilization effect was “saturated” in the 20th century.
There’s lots of hair on Moberg, which I hope to get to.
In 1998, Mann could never have dreamed this would be examined as it has been.
He should have just been truthful re R2 from the beginning.
The answer is tendentious and non-responsive. Mann decides to answer a different question than what was asked. What was asked is “did you do this”, not “should one do this”. He is so…ducking and weaving. Someone who behaves like this, is likely tendentious in science work as well. Very troublesome. I think that is why some of the “team” is distancing themselves from Mann.
And that, perhaps explains somewhat why RealClimate hasn’t attracted any sort of active audience such as this site has. The Hockey Team has to be so careful about what they will or won’t talk about that what’s left is a discussion of Hurricane Katrina and other pop-culture subjects.
This site is looser. I respect the intellect and am interested in the comments of the moderators there. Some of the audience is pretty simpleminded fanboy (we have some on our side too).
Really wish that Gavin or the like would come over here more. Like to learn from him and think he would push his own thinking. Sometimes, I worry that those guys let their politics get in the way of being curious Feynman type scientists. (I occasionaly gig Steve for that too…)
People may fail you. Devote yourself to truth and beauty or some like ideals and support people to the extent they share your respect for these concepts. I always thought an oath to the queen lame. An oath to preserve and protect the constitution, rational. To the extent I do the fanboy, it feels wrong. Like making a chess move that I know is inferior. It is to fail oneself.
That’s why we got rid of the monarchy and heriditary nobility.