Let science debate begin

The National Post ^ | Jan 27, 2005 | Terence Corcoran

[mista science]

Let science debate begin

Terence Corcoran Financial Post

Thursday, January 27, 2005

For some time now this page has been publishing comment on The Hockey Stick, the central piece of scientific evidence for the United Nation's claim that the world is warmer now than at any time in the last 1,000 years. Today we begin a major two-part investigation that delves deeper into the foundations for what may well be the most important economic, scientific and business graphic in world history.

[snip]

It is a story filled with intrigue, conflict and amazing facts about how science is made, especially climate science. It's also a story about the inner workings of science journals and, especially, the UN panel on climate change that is at the heart of climate politics and the economics of the Kyoto Protocol. Above all, the story threatens to rock the foundations of climate science. .....

Go to the article

[mista science]

Perhaps, the 'hockey stick' has even more meaning, the global warming claims are all pucked-up.

A bun is the lowest form of bread. ;-)

[mista science]

McIntyre & McKitrick found that the Mann et al. methodology included a data pre-processing step, ...

Muller, in his Technology Review article, gives a brief description of PCA and of Mann's flawed procedure that yielded the hockey stick.

.... McIntyre and McKitrick obtained part of the program that Mann used, and they found serious problems. Not only does the program not do conventional PCA, but it handles data normalization in a way that can only be described as mistaken.

Now comes the real shocker. This improper normalization procedure tends to emphasize any data that do have the hockey stick shape, and to suppress all data that do not. To demonstrate this effect, McIntyre and McKitrick created some meaningless test data that had, on average, no trends. This method of generating random data is called “Monte Carlo” analysis, after the famous casino, and it is widely used in statistical analysis to test procedures. When McIntyre and McKitrick fed these random data into the Mann procedure, out popped a hockey stick shape!

That discovery hit me like a bombshell, and I suspect it is having the same effect on many others. Suddenly the hockey stick, the poster-child of the global warming community, turns out to be an artifact of poor mathematics. How could it happen? What is going on? Let me digress into a short technical discussion of how this incredible error took place.

In PCA and similar techniques, each of the (in this case, typically 70) different data sets have their averages subtracted (so they have a mean of zero), and then are multiplied by a number to make their average variation around that mean to be equal to one; in technical jargon, we say that each data set is normalized to zero mean and unit variance. In standard PCA, each data set is normalized over its complete data period; for key climate data sets that Mann used to create his hockey stick graph, this was the interval 1400-1980. But the computer program Mann used did not do that. Instead, it forced each data set to have zero mean for the time period 1902-1980, and to match the historical records for this interval. This is the time when the historical temperature is well known, so this procedure does guarantee the most accurate temperature scale. But it completely screws up PCA. PCA is mostly concerned with the data sets that have high variance, and the Mann normalization procedure tends to give very high variance to any data set with a hockey stick shape. (Such data sets have zero mean only over the 1902-1980 period, not over the longer 1400-1980 period.)

The net result: the “principal component” will have a hockey stick shape even if most of the data do not.

[mista science]

Yearly temperature graphs:

Top one is Mann's bogus one. Bottom one is the corrected one, using correct statistical analysis.

Thanks for the graphs.

[mista science]

The first publicity I saw about the Canadians work was in MIT's Technology Review. Was this an independent report or one based on these articles, if you know?

The Technology Review article was dated October 15, 2004. The two National Post articles by Marcel Crok seem to have been written this year. (The Jan 27 and 28 dates are the dates of appearance in The National Post)

[DaveTesla]

A prime piece of evidence linking human activity to climate change turns out to be an artifact of poor mathematics.

In PCA and similar techniques, each of the (in this case,
typically 70) different data sets have their averages
subtracted (so they have a mean of zero), and then are
multiplied by a number to make their average variation
around that mean to be equal to one; in technical jargon,
we say that each data set is normalized to zero mean and
unit variance. In standard PCA, each data set is
normalized over its complete data period; for key climate
data sets that Mann used to create his hockey stick graph,
this was the interval 1400-1980. But the computer program
Mann used did not do that. Instead, it forced each data
set to have zero mean for the time period 1902-1980, and
to match the historical records for this interval. This is
the time when the historical temperature is well known, so
this procedure does guarantee the most accurate
temperature scale. But it completely screws up PCA. PCA is
mostly concerned with the data sets that have high
variance, and the Mann normalization procedure tends to
give very high variance to any data set with a hockey
stick shape. (Such data sets have zero mean only over the
1902-1980 period, not over the longer 1400-1980 period.)

The net result: the “principal component” will have a
hockey stick shape even if most of the data do not.

Mann used normalization.
He made his data conform to his own opinion.

[DaveTesla]

http://www.uoguelph.ca/%7Ermckitri/research/fallupdate04/update.fall04.html

Reluctance on the part of Mann et al. and Nature to produce the results for their "experiments, " and in particular for the AD1400 step, would be one thing if the source code that generated them were available; but the refusal to provide either one is completely unjustifiable, especially since Nature based its decision against our paper, in part, on claims about the RE statistics that can only be verified by looking at the "experiment" results. We surmise, based on our implementation of the methodology, that the R-squared and Coefficient of Efficiency (as this is defined in paleoclimate studies) statistics fail to reach statistical significance for the AD1400 step. It may also show that there are other problems in MBH98 besides the ones that we have described already. We already know that the adverse results from the bristlecone pine sensitivity study were not disclosed.

[DaveTesla]

Tech Central Station, Dr. Roy Spencer :
It took two non-climate people -- the global warming debate's equivalent of internet bloggers -- to do what should have been done by an independent paleoclimate research group. Both are Canadians: McIntyre is a consultant for mineral exploration, and McKitrick is a professor of economics. They received no outside funding for their work, so they can not be accused of being bought off. It surely won't help the IPCC's reputation that this latest development follows on the heels of the recent resignation of the IPCC's leading hurricane expert over editorial bias in the IPCC leadership.

Reaping the Hurricane (leading expert withdraws his name from U.N. report on global warming)

Tech Central Station, Dr. Roy Spencer :
The IPCC leadership can always fall back on the claim that they were only using published research, which is true. The criterion for scientific results to be included in governmental reports has usually been publication in the scientific literature, or in some cases the work only needs to be accepted for publication. But it now appears this is not sufficient. Unusual claims in science should be met with unusual skepticism, and this did not happen with the Mann et al. study. An increasing number of researchers have anecdotal evidence that the science tabloids, Nature and Science, select reviewers of some manuscripts based upon whether they want those papers to be accepted or rejected. In other words, it seems like the conclusions of a paper are sometimes more important that the scientific basis for those conclusions. Since those periodicals have profit and popularity motives that normal scientific journals do not, maybe the time has come to downgrade the scientific weight of publications in those journals, at least for some purposes."

I quit reading Nature and Science and Scientific American
years ago when they became leftist apologists.

[mista science]

Mann used normalization.
He made his data conform to his own opinion.

Muller did not criticize Mann for normalizing the data sets, but for using an incorrect normalization procedure.

In the paragraph preceeding the the one you quote back to me Muller goes to some length not to accuse Mann of deliberate falsification (or so it seems to me)

Suddenly the hockey stick, the poster-child of the global warming community, turns out to be an artifact of poor mathematics. How could it happen? What is going on? Let me digress into a short technical discussion of how this incredible error took place.

I interpret this as a hint to Mann to let it go.

Later in the article he is more direct: it's time to move on.

A phony hockey stick is more dangerous than a broken one--if we know it is broken. It is our responsibility as scientists to look at the data in an unbiased way, and draw whatever conclusions follow. When we discover a mistake, we admit it, learn from it, and perhaps discover once again the value of caution.

We know that McIntyre and McKitrick were turned down by Nature (as I recall), that they did an end run around Nature by posting all the info on their own web site (a part of which you link to me in your second post), and that now their work has been accepted for publication in a major peer reviewed journal. And that takes us back to where we started with Terence Corcoran: Let science debate begin

[DaveTesla]

Reconstructing Large-Scale Climatic Patterns from Tree-Ring Data
Harold C. Fritts Professor Emeritus (Dendrochronology)(the master of bristlecone pine tree rings himself)

[E.G.C.]

BTTT!!!!!!

[DaveTesla]

Naaaaa.
The IPCC and the U.N. would never falsify data.
Especially when it came to redistributing America's wealth.
(To themselves I may add.)

[Carry_Okie]

Let me digress into a short technical discussion of how this incredible error took place.

How charitable.

[punster]

---

Perhaps, the 'hockey stick' has even more meaning, the global warming claims are all pucked-up.

A bun is the lowest form of bread. ;-)

---

LOL

[gobucks]

It's not too hard to see I agree.

I wish this conflict were as easy on the evo threads...

[elfman2]

Thanks! That’s what I most wanted in order to understand what went wrong.

I forgot most of what’s necessary from statistics to really get that, but I think it’s saying that quirks in the program they chose to use led them to normalize 20th century data in a different set from earlier data, and tie only the 20th century data set to modern temperature readings. And that’s behind the false claim that world temperatures are rising.

[gobucks]

Outstanding. Too bad we can't good figures like that for the evo threads ....

[shubi]

The science side has plenty of good statistics. It is the creationist side that lacks any science. ;-)

[gobucks]

Keep staring at this picture and keep saying:

evolution is straight and true...

evolution is straight and true ...

[DaveTesla]

Model simulations of any system that is considered to be
chaotic (I like to call them discontinuity's) are
particularly sensitive to the conditions set
for the simulations.

Simplify and Exaggerate.
And Exaggerate they do.