Home > Environment, Science > Adventures in social network analysis

Adventures in social network analysis

July 15th, 2006

The latest round in the Republican War on Science is a report prepared for US Representative Joe Barton aimed at discrediting the ‘hockey stick’ analysis of global temperatures first undertaken by Mann, Bradley, and Hughes, and subsequently supported by many other studies. For reasons that aren’t entirely clear, this peripheral issue in the analysis of climate change has attracted disproportionate attention from denialists, most notably Ross McKitrick and Steve McIntyre. One result was that the US National Academy of Sciences recently reviewed the work, reaching conclusions broadly supportive of MBH.

The report for Barton was prepared by three statisticians, Edward Wegman, David Scott and Yasmin Said , and its only novel contribution is a social network analysis, which is meant to show that the various independent studies aren’t really independent and that peer review has broken down, since the same group of interlinked academics is reviewing each others’ papers.

Kieran Healy and Eszter Hargittai at Crooked Timber are experts on this stuff, and I’ll be interested to see what they have to say. But in the meantime, I have a couple of observations (feel free to correct errors in my interpretation).

Two network analyses are presented, of which most weight is placed on the first, consisting of a database of 43 individuals. The conclusions reported by Wegman, Scott and Said are as follows:

The block (cluster) structure is very clear. Michael Mann is a co-author with every one of the other 42. The black squares on the diagonal indicate that the investigators work closely within their group, but not so extensively outside of their group. The occasional off diagonal boxes indicate that some investigators have joint papers with investigators outside of their immediate group. The order of the authors on the vertical and horizontal axes is the same. Unfortunately, there is overprinting on the horizontal so that individual authors are not readable. However, it is immediately clear that the Mann, Rutherford, Jones, Osborn, Briffa, Bradley and Hughes form a clique, each interacting with all of the others. A clique is a fully connected subgraph, meaning everyone in the clique interacts with every one else in the clique.

The group of 43 is described as follows

The first specifically focusing on Dr. Mann was developed by first considering all of his co-authors and then examining the abstracts produced by the co-authors. We focus on Dr. Mann because he is the lead author of MBH98/99 and because he is extremely influential in this area as can be seen by his high degree of centrality.

In other words, if I understand things correctly, the first key finding is that (drumroll) Mann has co-authored a paper with every one of his co-authors This obviously demonstrates his “centrality” to the group consisting of his co-authors.

The finding that “Mann, Rutherford, Jones, Osborn, Briffa, Bradley and Hughes form a clique, each interacting with all of the others” can be verified using Google. All those listed were among the authors of:

Mann, M.E., Ammann, C.M., Bradley, R.S., Briffa, K.R., Crowley, T.J., Hughes, M.K., Jones, P.D., Oppenheimer, M., Osborn, T.J., Overpeck, J.T., Rutherford, S., Trenberth, K.E., Wigley, T.M.L., On Past Temperatures and Anomalous Late 20th Century Warmth,Eos, 84, 256-258, 2003.

This automatically qualifies them as a “clique”. So the second finding can be rephrased as (another drumroll) Some of Mann’s papers have lots of co-authors BTW, it appears that Wegman, Scott and Said didn’t catch all the co-authors.

The second analysis uses the 75 most published authors in the field (a much more reasonable choice) and comes to the conclusion

There are some interesting features. Although Michael Mann remains an author with high centrality, Tett, Briffa and Cook emerge as belonging to their own cluster and they also exhibit high centrality. Schweingruber and Collins also appear to have relatively high centrality. One interesting observation is that although Tett is fairly central, he has no direct linkage to Mann. Similarly the Gareth Jones-Allen-Parker- Davies-Stott clique also has no direct linkage to Mann. There are two Joneses. Gareth Jones is not the same person as the person previously labeled as Jones.

My summary (no drumroll this time). There are several leading research groups in this field. Some of them are fairly closely linked to Mann and his group and others are not.

Categories: Environment, Science Tags:
  1. blitzed
    July 15th, 2006 at 17:09 | #1

    I don’t think Strve McIntyre has ever denied global warming…..But he certainly is denying that the temperature of the earth will warm according to the graph of a hockey stick.
    It is a fascinating story with many aspects to it including the cliques and peer reviews you mention
    Steve McIntyre has been deconstructing Mann’s theory graph by graph, proxy by proxy,formula by formula
    Heavyweight statisticians like Wegman are now getting on board and the theories are starting to unravel
    We find ourselves at a very interesting stage in the theory of Global Warming

  2. stephan harrison
    July 15th, 2006 at 21:26 | #2

    Two observations. First, whether or not the MWP or LIA were global in extent has nothing to do with AGW, which is based upon the known radiative effect of greenhouse gases and the amounts we are pumping into the atmosphere. Second, hockey sticks occur using other proxies (glaciers for instance) and these clearly have nothing to do with C02 fertilization, bristlecone pines etc. I’m glad to see that the (sensible) sceptics have moved from “there is no warming” through “the record is contaminated by urban heat islands” and are now agreeing that warming is happening. It won’t be long before they are on board the attribution argument too!

  3. July 15th, 2006 at 21:29 | #3

    blitzed – “We find ourselves at a very interesting stage in the theory of Global Warming”

    As MBH98 has absolutely nothing to do with the theory of anthropogenic global warming I don’t know how you come to this conclusion. MBH98 only places recent warming in a historical context – no more no less. The foundations of AGW were laid long ago with research into greenhouse gases and their actions in the atmoshere.

    M&Ms ‘studies’ and this later study, none of them peer reviewed, is only intended to inject what in a court of law is termed ‘reasonable doubt’ They hope to prove that MBH98 is false and therefore AGW is false. Then we can go on releaseing as much CO2 as we like and people, who already are obscenely rich, can make even more money selling the products that release this CO2. There are 2 major problems with this:
    1. Despite M&Ms claims MBH98 is not a cornerstone of the AGW argument.
    2. Science is not a court of law.

    However I realise that this is not a scientific debate. M&M and their backers are running a hearts and minds campaign for the opinion of people who perhaps are not well versed in the facts of AGW. Portraying Dr Mann falsely as producing fraudulent science they are hoping to cast doubt in the minds of the public who cannot tell the difference between one study from the thousands that make up the case for AGW and the false claims that false science is harming the “American way of life” which apparently is non negotiable.

    The real tragedy is that these actions have been effective and have worked to prevent action on global warming that could have minimised any climate change that will result from this until it is perhaps too late.

  4. blitzed
    July 16th, 2006 at 11:01 | #4

    Ender: It is interesting that you say Global Warming is back to being a theory
    I thought the debate was over!
    Is it the beginning of the end or the end of the beginning?

  5. blitzed
    July 16th, 2006 at 11:14 | #5

    You are quite correct in saying that it is not a scientific debate
    Enviromentalists want us to consume less less less
    Left leaning types want to impose restrictions on energy use (especially Americans with their damn SUV’s) India and China get a free pass
    And the scientists definitely want more research $$$$

  6. mg
    July 16th, 2006 at 11:40 | #6

    Actually, “Global Warming” is not a theory, it’s an observation. There are theories that attempt to explain this change in the energetics of our planet’s atmosphere.
    Some of them require you to believe that the fact that global temperatures started to rise at about the same time as our CO2 producing industries really started to kick into overdrive is just a coincidence. Some scientists choose not to put too much weight in unlikely coincidences unless shown overwhelming evidence.

    ps: “gotcha” moments involving use of the word “theory” aren’t much fun in science. They only expose your ignorance of the meaning of this word (…for fun times look up ‘Theory of Relativity’).

  7. July 16th, 2006 at 13:58 | #7

    blitzed – “It is interesting that you say Global Warming is back to being a theory”
    The word theory is used in its scientific context. Universal Gravitation and thermodynamics are theories.

    “Enviromentalists want us to consume less less less
    Left leaning types want to impose restrictions on energy use (especially Americans with their damn SUV’s) India and China get a free pass
    And the scientists definitely want more research $$$$”

    No the need to use less resources is set by the logarithmic growth law. Here is an extremely interesting lecture on it by probably a lefty maths professor with his left leaning mathematics. http://www.globalpublicmedia.com/lectures/461
    Listening to it will see why 1% growth per year will double the size of anything in 70 years. China and India are facing these problems and will not get a free pass as the environmental problems are already biting them.

    Lets examine the research dollars thing. Scientists want more money to resolve the questions that you pose. The research grants are quite small and every dollar must be accounted for in the most stringent way and must be spent on research. The researcher’s salary is set by scales.

    Contrast this with the dollars that flow from the vested interests that stand to lose by reduced use of fossil fuels. There is no accounting and the amounts dwarf the research grants. M&M, Singer et al can spend the money on whatever they choose with no scrutiny. However there is one place where the money can be seen. Smokey Joe got his name from the extreme willingness he has shown in accepting donations from the coal and oil industries and that is in plain sight. Last year his donations from this sector was $523 099.00.

    There is a latin phrase that translates to “who benefits”. In this case it is clear the fossil fuel industries benefit from continued inaction on global warming.

    The social network analysis has opened up a can of worms that M&M really did not want opened. By analysing MBH’s network they are exposing themselves to the same scrutiny. I mean that would only be fair. It is easy to see Rep Barton’s network and I am sure the same could be done for WSS and M&M. Do you really want this exposed?

  8. July 16th, 2006 at 14:03 | #8

    Correction – sorry I am a year out. Rep Bartletts donations in 2004 were that amount.

  9. blitzed
    July 16th, 2006 at 14:25 | #9

    Who are the dark forces behind McIntyre and his tin-pot blog.Who is handing out the $$$$. And you are sure there is a network there
    Intrigue upon intrigue
    Disregard the fact that he is changing the direction of the GW debate through clear,logical reasoning and concentrate on the dark forces

  10. Ernestine Gross
    July 16th, 2006 at 15:10 | #10

    “There are several leading research groups in this field. Some of them are fairly closely linked to Mann and his group and others are not. ”

    So what?

    A social network analysis has nothing to say on the validity of a scientific method (including the formulation of theories) and its application.

    It might be an interesting analysis after one or several pieces of work have been shown to be fatally flawed on scientific grounds. But I understand from JQ’s post that this is not the case with the material that constitutes the subject matter of the social network analysis in question.

    Incidentally, is there any statistical information on the frequency of blitzed having a conversation with blitzed?

  11. July 16th, 2006 at 15:58 | #11

    blitzed – “Disregard the fact that he is changing the direction of the GW debate through clear,logical reasoning and concentrate on the dark forces”

    No he is picking apart one study with misrepresentation, leaving out data sets and actual mistakes including the howler of confusing radians and degrees.

    So what is next on this crusade for scientific purity – string theory audits or perhaps a look inside the drug industry ‘studies’. I don’t think there will be many takers for auditing these especially not from Smokey Joe. His next major contributer is the health and drug corporations.

  12. July 16th, 2006 at 15:59 | #12

    blitzed – BTW how did you go with the maths lecture – it is really worth a look.

  13. blitzed
    July 16th, 2006 at 19:22 | #13

    Ernestine: Thanks for the advice. I’ll stop talking to myself and talk to you
    If you go to the Wegman report linked in JQ’s post you will find that there are fatal flaws in the hockey stick on statistical grounds. It is kaput,broken pushing up the daisies.It is an ex-hockey stick
    So you are quite correct to say that the social network analysis is quite interesting

  14. Ernestine Gross
    July 16th, 2006 at 20:13 | #14


    1. There might be a misunderstanding which may be due to the delay in my post. My reference to blitzard talking to blitzard relates to my observation that Enders quoted you and you treated your own words as if they had originated with Enders. The sentence in question is: “We find ourselves at a very interesting stage in the theory of Global Warming”.

    2. My post referred to the social network analysis. I understand the Wegman report contains the social network analysis. Your post does not contain new information relevant to my post.

  15. July 16th, 2006 at 20:40 | #15

    I recall Keating’s famous “J-Curve” … that’s the “J” that goes straight down, then does a right angle turn, and keeps going. So did the economy.

    That’s the “L-Curve”.

  16. July 16th, 2006 at 21:20 | #16

    blitzed – “It is kaput,broken pushing up the daisies.It is an ex-hockey stick”

    Keep talking you might convince someone this way.

  17. Seeker
    July 16th, 2006 at 23:57 | #17

    …including the howler of confusing radians and degrees.

    No sh*t? Did he really do that? That is like confusing an apple and a banana, in broad daylight.

  18. July 17th, 2006 at 08:19 | #18

    Seeker – “No sh*t? Did he really do that?”

    Yep – http://timlambert.org/2004/08/mckitrick6/

  19. Roger Jones
    July 17th, 2006 at 11:21 | #19

    This analysis is interesting.

    I’m an IPCC lead author, therefore have shared co-authorship with (let’s say hundreds) of other co-authors.

    Therefore, we are all as biased as each other.


    According to this reasoning, Fairfax and News reporters can’t both be telling the truth. Or Fox and CNN. Or men and women. Oh dear.

  20. blitzed
    July 17th, 2006 at 17:06 | #20

    Diozpora: Aah Keating and his “J” Curve. It brings back so many unhappy memories.
    And some people believed it too….

    This is the captain of the S.S. Hockeystick
    We have taken a torpedo amidships
    Abandon Ship Abandon Ship
    May Day May Day
    Gurgle gurgle

  21. T J Olson
    July 18th, 2006 at 21:22 | #21

    Famed hurricane prediction expert William Gray at Colorado State University (USA) has joined “the denialists.�

    Actually, according to this survey of 530 climatologists a few years ago, “the denialists� have lots of company. While these scientists definitely lean toward anthropogenic global warming, there is definitely no “consensus.�

    Far from being accurately characterized as “right wing� as John Quiggin believes, neither Steve McIntyre nor William Gray (see article) are sensibly described as such. The matter of ACW has become a religious test for many people – an article of faith beyond falsifiability, as evident here on this thread.

    That’s unfortunate. Considering that billions of US dollars annually are spent on such research (some 90% of the world’s total), one would think that the people had a right to know if such consequential work could be corroborated or not. Apparently, the journal “Natureâ€? believed that even knowing about dissent among climatologists was not important enough to publish (see second link above).

  22. T J Olson
    July 18th, 2006 at 21:33 | #22

    Finally, JQ is under the misapprehensions of the media when it come to the June NAS report. He writes: “One result was that the US National Academy of Sciences recently reviewed the work, reaching conclusions broadly supportive of MBH.”

    In fact, if you read chapters eight and ten of that report, you’ll see that is was quite critical if not devastating in its critique of the MBH methodology. Unfortunately, the NAS committee unilaterlally changed its remite from important specifics about paleoclimatology and methodology the US Congressional sub-committee gave it into a very general assessment. This meant shoe-horning the hearing it conducted in March which had Mann and M&M making prese ntations (although Mann left immediately) into a popular albeit misunderstood framwork about ACW. Thus, media reports converted the NAS study’s “plausible” interpretations about warming into most “probable.” And JQ therefore mistakenly believes it was quite supportive of MBH.

  23. Jo Calder
    July 19th, 2006 at 00:14 | #23

    Ender: you mistake “McKitrick” for “McIntyre”. Reading the URL you supplied:

    Yep – http://timlambert.org/2004/08/mckitrick6/

    provides something of a clue in this respect.

    Cheers, — Jo

  24. July 19th, 2006 at 08:26 | #24

    Jo Calder – Yeah sorry I really should have said M&M.

  25. Terje
    July 19th, 2006 at 11:11 | #25

    In todays Australian newspaper Alan Wood has his say on this topic.


    Yet the IPCC used the hockey stick in its publications, media releases, press conferences – where senior IPCC figures sat with the chart as a backdrop – and, for a time, incorporated it into the IPCC’s logo.

    In an article last week in Canadian newspaper the National Post, McIntyre and McKitrick say the IPCC’s lead author, who selected Mann’s hockey stick for prominent display, was none other than Mann himself. They quote eminent US climate science academic Kurt Cuffey as saying the IPCC’s use of the hockey stick sent “a very misleading message”.

    The IPCC seems to be a little like the notorious Ministry of Truth.

  26. Ernestine Gross
    July 19th, 2006 at 13:39 | #26

    It is fascinating to watch the output of the PR machineries, headquartered in the USA. In a sense, it is of no consequence because:

    The subject of global warming goes beyond politics and the government of the day. In the case of Australia, the Head of State is Queen Elizabeth II. I understand Her Majesty, the Queen, has made a statement on this matter after consultations with knowledgable people of her choice. The US does not have a monopoly on scientists. I do not recall Her Majesty having referred to ‘hockey stick’ at all.

  27. Terje (say TAY-A)
    July 19th, 2006 at 14:43 | #27


    I am not sure what your point is. Perhaps if you type slower I will understand it better.


  28. July 19th, 2006 at 14:59 | #28

    I am with Terje on this. I would, however, take issue with one of your statements: “[t]he subject of global warming goes beyond politics…”. This is simply wrong. This is the sort of discussion for which politics exists.

  29. Ernestine Gross
    July 19th, 2006 at 16:02 | #29


    It would seem to be impossible to determine whether you are right in telling me that my usage of a phrase is wrong because there are multiple ‘views’ on what politics is.

    You can view the ‘views’ in your often preferred reference source:

    (Did I write slowly enough? – only joking.)

  30. Terje (say TAY-A)
    July 19th, 2006 at 17:45 | #30

    Did I write slowly enough?

    Ah, much better.

    Now please re-type the earlier piece at the slower pace.

  31. jquiggin
    July 19th, 2006 at 19:13 | #31

    TJ Olson, all the sources you cite (SEPP, MckItrick, Gray) are well-known as extreme rightwingers, and the Bray survey you mention is a politically motivated piece of nonses.

    Terje, I think the correct conclusion from the passage you cite is “If Alan Wood is right, the IPCC is like …”. On what basis do you regard Wood (an economic journalist) as authoritative in such matters.

    I’m an economist, I’m confident I’m better informed on this topic than Wood is, and I don’t suggest that people should take my word for it on scientific issues – I point to the actual scientists involved.

  32. July 20th, 2006 at 08:28 | #32


    If Alan Wood is right, the IPCC is like the ministry of truth.


    P.S. Are you saying that you think Manns hockey stick is correct?

  33. July 20th, 2006 at 15:52 | #33

    I apologise and withdraw. It should have read “I believe it to be simply wrong”.

  34. July 25th, 2006 at 17:00 | #34

    The commentary has largely missed the point of the bloglet – that social network analysis will demonstrate in any academic field some grouping of individuals who are like minded. These are often referred to as “schools of thought” within a discipline. Only a very few of what Keith Windshuttle would call “the Sydney Line” don’t get it that this is common. Pity that.

Comments are closed.