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All IPCC definitions taken from Climate Change 2007: The Physical Science Basis. Working Group I Contribution to the Fourth Assessment Report of the Intergovernmental Panel on Climate Change, Annex I, Glossary, pp. 941-954. Cambridge University Press.

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Comments 124101 to 124150:

  1. Did Phil Jones really say global warming ended in 1995?
    As Joe Romm puts it the problem is in the question, something like asking "are you still beating your wife?". If you by instinct answer "no, of course" you're admitting that once you did. Tamino gives another example. You have been measuring a child's height for years to follow his growth. If asked if you can prove that there has been a stistically significant growth in the last week you have to say no, so the child is not growing any more. What i want to say is that there is no meaningfull answer to a meaningless qustion but reformulating it.
  2. Is CO2 a pollutant?
    For anyone who wants to see a reasonably detailed deconstruction of Bob Armstrong's arguments, I recommend his and my exchange at S&R here, down toward the bottom: http://www.scholarsandrogues.com/2009/11/20/climategate-not-likely/ Furthermore, I dealt with the bulk of his arguments using physics (complete with the math, calculations, derivations, etc.) in three documents also available at S&R: http://www.scholarsandrogues.com/wp-content/uploads/2009/11/BobArmstrong.pdf http://www.scholarsandrogues.com/wp-content/uploads/2009/11/emissivity.pdf http://www.scholarsandrogues.com/wp-content/uploads/2009/11/Venus.pdf Bob never responded after I posted the last two .pdfs, yet here we find him making some of the same wrong claims that I am pretty confident I disproved. The only argument he made at my site that I didn't take on is his MgO sphere example from above, but I'm pretty sure that he's misunderstood it badly. I think that the power in the interior of his hypothetical room should be constant, so the MgO ball ends up being the same temperature as the room no matter what it's albedo is (power density drops as r^2 as you leave the walls of a spherical room and move toward the center, but the area of the sphere drops as R^2 too, leaving the power constant). But I didn't prove it rigorously with calculus. If anyone reads those docs and sees major flaws in my math, please let me know. I'm planning on using the Venus doc as a baseline for a "debunking this bad argument" post at some point (or maybe John can. :)
  3. Did Phil Jones really say global warming ended in 1995?
    That's a very good point, GFW. Perhaps Phil Jones, in his reply, should have said "there is no statistically significant change from the previously established warming trend". Easy to second-guess in hindsight, though, isn't it?
  4. Did Phil Jones really say global warming ended in 1995?
    I just realized what the correct rebuttal is to people who choose short recent time periods and say things like "you can't reject the null hypothesis, so there's no statistically significant warming". Here's the thing. The upward linear trend since the mid 70s (30+ years) is known and is easily shown to be statistically significant. So the null hypothesis for short time periods near present is "that rate of warming continues". And guess what? There is no cherry pick that will allow anyone to reject *that* null hypothesis. We can easily quantify what it would take to reject continued warming. When that condition is met (and I'm not expecting it) then climatology would have some 'splaining to do. But only then, and it sure isn't likely.
  5. The Dunning-Kruger effect and the climate debate
    KLR @ #78: There is a nice graphic presentation of the consensus on this issue. John has it in this article. Seems very clear to me.
  6. Did Phil Jones really say global warming ended in 1995?
    Again, Arkadiusz Semczyszak, you are mistaken. If you take a look at the GISS data, you'll see there is a very good relationship between the apex & nadir of each solar cycle & the warmest & coolest years within that cycle. Even if that were not so, the 2000-2009 portion of the current cycle was by no means normal-its the deepest solar minimum in over a century-& it lasted around 4 years-yet still temperatures moved generally upwards. Lastly, it doesn't alter the fact that, beyond the normal cycles, solar activity has been trending downward for the last 30 years, yet temperatures have been trending upwards over this same time period. I've seen several papers which conclude that the correlation between solar activity & deltaT ceased at least as early as 1979 & possibly as far back as 1950.
  7. The Dunning-Kruger effect and the climate debate
    Someone should have a graphic presentation of the consensus on this issue. Recently I saw a graph illustrating the number of climatologists signing onto some anti-AGW petition versus those declining, it was quite striking. More of that, please. Show just how much of a minority your opponents are, and how lopsided the qualifications of the respective camps are. logicalscience.com is a good start but you need to direct your efforts towards the unlettered, to say nothing of educated people who lack the time to read page after page of documents attempting to reach a conclusion. There needs to be a clearinghouse for links to info of this sort as well. The extant resources I find lacking in various ways, it should be a dedicated endeavor, rather than expending enormous amounts of time debating people with irrational emotional attachments to political postures, which accounts for the bulk of the anti-AGW sentiment in the public, not any true spirit of scientific inquiry. You may enjoy attempting to knock sense into random heads but we are really wasting our time here arguing with these people.
  8. Did Phil Jones really say global warming ended in 1995?
    Steve L. @#59 "As D.Marsupial says in #24, one fails to reject the null hypothesis; one doesn't accept the null hypothesis" Yes, you are right; that is the way I should have put it.
  9. Did Phil Jones really say global warming ended in 1995?
    When Steve L wrote "if the effect size and sample size are small relative to the noise in the system," he was referring to statistical power.
  10. Did Phil Jones really say global warming ended in 1995?
    The important question about trends is not about statistical significance, which is very much dependent on the methods used, but of stability. Starting with the latest records, and extending the observation period backwards, does the trend coefficient stabilize in a reasonable time, and on what? Trends for shorter periods may very well be statistically significant - that is mostly a question of fluctuation, noise, level. But are they stable? The 1995-2009 GISS trend of ca 0.15 degC/decade seems to be a relatively stable figure. To get much higher values, you have to cherry-pick observational series, and likewise, to get much lower values, you have to omit a lot. Interestingly, the GISS and UAH trends are very close to each other. Of course, there is really no scientific significance associated with the 0.05 level, it's just one practical about reporting and one formal about what we, by convention, may report. Only great fools would disregard a result at the 0.06 level because "it is not significant" - after all, it's 94% chance there is something there. Likewise, as you would get a 5% significant result by chance one in out of 20 trials, you really can't "trust" a randomly chosen 5% result. It's all about looking at the whole picture of information. And when we can get results as significant as we like just by extending the observation period a little, any talk about "null hypothesis acceptance" her may be utterly misleading. The rank viewpoint may be useful, but I think it should be used carefully in simplistic statistical modeling: If, for instance, all the last 10 years are among the top 30 on record (I haven't checked that, just an illustration, but it's not too far off), it's far too early to talk about "cooling", even if we may have entered into a new period, with new trends. We just have to await the further development.
  11. Did Phil Jones really say global warming ended in 1995?
    Re: TobyJoyce in #55 -- it's good for you to provide a basic summary (and I look forward to the one John Cook promised in #19). However, I'd like to take issue with your last statement that "the null hypothesis would be accepted." As D.Marsupial says in #24, one fails to reject the null hypothesis; one doesn't accept the null hypothesis. This sort of terminology is adopted because the null hypothesis (hypothesis of no difference) may be statistically indistinguishable from the alternate hypothesis if the effect size and sample size are small relative to the noise in the system.
  12. Did Phil Jones really say global warming ended in 1995?
    Oops, Binomial formula should be 9*0.5^8*0.5^1=0.0178
  13. Did Phil Jones really say global warming ended in 1995?
    There is another way we can look at this borrowed from quality assurance methods. It is a bit crude, but it looks to me like 8 of the last 9 points in Figures 1 and 2 are above the mean of all the points (which seems to be about 0.35). If we set the probability of being above the mean to be 0.5, then it just an application of the Binomial Theorem - the probability of that happening is 9^0.5^8*0.5^1 = 0.0178, which makes it significant at the 5% level. The deduction is that there is an "upward shift in the mean" between the start of the sequence of points and the end. In QA, this is called a "run above the mean". If you take all the points, 9 are above the mean & 6 below, which has a 0.1527 probability.
  14. Is CO2 a pollutant?
    suibhne If your complaint is going to be based on the Second Law, then rest assured that nowhere in the system is there a net flow of heat from a cold point to a warmer point. Heat is always flowing in the correct direction.
  15. Did Phil Jones really say global warming ended in 1995?
    There seems to be a bit of confusion about "statistical significance". Statistical significance is given usually as a p-value which is the probability that the data occurred by chance alone. If an hypothesis has a low enough p-value, we tend to accept it because the evidence (data) is therefore unlikely to be by chance alone. Ronald Fisher, who introduced p-values, set 5% and 1% as threshold values for significant *"highly significant" results. But there is an element of subjectivity about p-values. Suppose your p-value is 0.0505? Is that significant? Some practitioners suggest just publishing the p-value and then deciding. Jones did not publish his p-value but it must have been less that 10%, or quite close to 5%. The null hypothesis in this case is that the slope of the fitted trend line through the points = 0. If the 95% confidence interval for the slope contained 0,then the null hypothesis would be accepted.
  16. Is CO2 a pollutant?
    suibhne, you believe Tom Dayton and carrot eater are laboring under a misunderstanding, but you don't explain how. Could you do that? Thanks!
  17. Is CO2 a pollutant?
    Tom Dryton and carrot eater It seems to me you are in need of some grounding in thermodynamics. Could I recommend Equilibrium thermodynamics by C.J.ADKINS The mechanisms you describe seem contradictory and unphysical.
  18. Did Phil Jones really say global warming ended in 1995?
    Tom Dayton,John Russell Read the Nature interview very revealing!..... and a reply from Keenan, D. J. underneath article. Energy & Environment, 18, 985-995 (2007).
  19. Is CO2 a pollutant?
    Here's an augmentation of CBDunkerson's response regarding CO2 "lifetime": CB used the correct phrasing "how long CO2 levels remain elevated," because that is what matters--the total amount of CO2, not which individual CO2 molecules make up that level. Often the blogosphere uses the ambiguous term "CO2 lifetime." That can be taken to mean "duration of an individual CO2 molecule's residence in the atmosphere," which is irrelevant. If one molecule (Lucy) is absorbed out of the atmosphere, with the consequence that that particular absorbing mechanism now cannot absorb a different molecule (Ethyl) which newly has entered the atmosphere, then the level of CO2 has not dropped due to the absorption of Lucy. Lucy and Ethyl can play tag forever, with one at a time being in the atmosphere, with the consequence that the level stays constant. What matters is the balance between emission and absorption, from all sources and sinks. When emission increases faster than absorption, the level in the atmosphere increases, despite the constant swapping of individual molecules.
  20. Is CO2 a pollutant?
    Bob Armstrong, on the issue of how long CO2 levels remain elevated (your other points having been addressed by carrot eater)... you should consider the ice core record. You dismiss estimates of centuries as ridiculous, but in fact every time there has been a CO2 increase of ~100 ppm (which is about where we are over the pre industrial revolution level) in the ice core records it has taken place over a period of a few thousand years... and then required ~100,000 years to return back down to the previous level. Mere centuries are thus a very 'hopeful' estimate when compared to every past instance for which we have data. It is unfortunate that you are so certain of the validity of your errors. Had you shown a more open mind you might have learned something.
  21. The Dunning-Kruger effect and the climate debate
    HumanityRules at 19:54 PM on 16 February, 2010 Helps to remember that over the long term climate variability one way or another imposed by solar fluctuation will dither widely while more or less exhibiting no net long term change (unless we go forward millions of years). On the other other, what we know of the behavior of C02 when it is illuminated by IR tells us it will impose a steady net increase in the amount of heat energy retained within our atmospheric envelope. I think it's easy to overlook this important difference between one driver of variability (or net variation) and another. what we know now tells us that given a few decades, added C02 in sufficient quantities will always win over solar forcing as a driver of climate change. Also, having noticed a common error creeping into this thread, I'm going to be redundant yet again (r2) and point out that we devote fanatical amounts of engineering expertise to controlling anthropogenic emissions of substances also found as natural constituents of the atmosphere. C0 is a prime example. So it's a fallacy to say that C02 in excessive amounts is not a pollutant. A quick check of the dictionary will help with this.
  22. Did Phil Jones really say global warming ended in 1995?
    suibhne @44 I think I'm right in saying that the CRU have pointed out that they do not generate any original data (records)-- that is, they don't go off to the South Pole, or wherever, to gather readings -- so if Jones said he is not very good at keeping records, it doesn't necessarily mean that he's lost original data, or not know where the original data exists. As I said -- in effect -- earlier, he's a dolphin that's found himself in a pool of sharks. He might be more intelligent and knowledgeable than they are, but his teeth are seriously inadequate.
  23. Is CO2 a pollutant?
    Bob Armstrong: Please review more carefully what Kirchhoff's law actually requires. It should be in any decent physics book. It does not require materials to be grey bodies, which is good because we can clearly see that they are not. Things do have different colors, after all. It only requires that the absorptivity and emissivity be equal to each other at a given wavelength. It does not require either quantity to be constant over wavelength. You can see this emipirically. Look up the emissivity of snow. In the wavelength range where snow might emit (long IR), the emissivity is close to 1. But of course snow is a poor absorber of visible light. Wavelength matters.
  24. Did Phil Jones really say global warming ended in 1995?
    But suibhne, the 2008 paper affirmed the conclusions of the 1990 paper, while lacking the possible flaws of the 1990 paper.
  25. Is CO2 a pollutant?
    suibhne: It isn't a matter of a time delay. The issues are that CO2 radiates back towards the Earth (the surface sees more radiation than it used to), and that the emission that finally makes it out to space is emitted from higher up in the atmosphere, where it is colder (less radiation is leaving the earth system than is arriving, so the system has to warm up). With nitrogen, you get none of that. By the way, CO2 doesn't always instantly radiate a photon as soon as it absorbs one. It can collide with neighboring molecules and thus warm up that pocket of air. But that's still fine; the CO2 will still emit at some rate set by the local temperature. These sorts of things are easily learned about in a textbook that covers radiation transfer in the atmosphere. I suggest simply getting one.
  26. Did Phil Jones really say global warming ended in 1995?
    angusmac @47, see the comments policy for how to post figures. Hopefully you can relate your graph to the discussion.
  27. Did Phil Jones really say global warming ended in 1995?
    Phil Jones may rewrite part of 1990 report. Nature online 16/2/2010
  28. Did Phil Jones really say global warming ended in 1995?
    oracle2world: Is it accurate? 'There has been no warming since 1995' is a very different statement from 'there has been no statistically significant warming since 1995'. In Jones' set there is a warming trend, and every year after 2001 has been warmer than 1995. There has been warming. It is not statistically significant because a certain combination of known noise could recreate that trend in 5%+ of cases. Of course, if you think my stats understanding is wrong, point me to where I can read up and fix it.
  29. Did Phil Jones really say global warming ended in 1995?
    Tom Dayton I Hope that you understand why I remain sceptical about the disputed Chinese readings. No doubt the issue will be examined by each of the two inquiries.
  30. Is CO2 a pollutant?
    Tom Dayton I was in part answering post 119, who if correct with instantaneous absorption and emission of IR, would imply almost that nothing had happened and since IR moves at 3*10^8m/s, then any delay is negligible. Water vapour is still in the atmosphere(in much greater quantities) and is an even better IR absorber. Further conduction from Earth surface by all atmospheric gases plus convection including wind will distribute and even out the Earths surface temperature
  31. Did Phil Jones really say global warming ended in 1995?
    Is it possible to post a chart on this site? I have an intersting graph based on current GISS data and a paper by Hansen et al, 2006, which I would like to post. This shows that we are currently tracking below the zero-emissions trajectory for global warming.
  32. Jeff Freymueller at 03:15 AM on 17 February 2010
    Did Phil Jones really say global warming ended in 1995?
    #41, oracle2world. Just one question. First, read post #21. If the warming trend from 1995-2009 is not staistically significant, but the trend from 1994-2009 IS statistically significant, as is the trend from any year prior to 1995 through 2009, what do you think the headline should be? #43, John Russell, I got a similar impression of Jones from the transcript. He was spin-free. Certainly it would have been better for him to have said, "the trend from 1995-2009 is not significant, but the trend from X-2009 is. The reason for the difference is that 1995-2009 is too short a time span." But we were not the ones sitting there in front of the TV cameras -- it's easy to second-guess.
  33. Polar bear numbers are increasing
    jasonblanchard, at least one species of seal is indeed at risk. But, controversially, the U.S. recently denied a request to list them as endangered.
  34. Increasing CO2 has little to no effect
    Matt, the implication of what Stuart just explained in his next-to-last paragraph is that the energy coming from the Sun to the Earth is in the wrong wavelengths to be much absorbed by CO2, but the energy being emitted by the Earth is very much in the right wavelengths to be absorbed by CO2.
  35. Did Phil Jones really say global warming ended in 1995?
    suibhne, regarding the "disputed Chinese readings," Phil Jones and colleagues have posted a response.
  36. Polar bear numbers are increasing
    "No sea ice means no seals which means no polar bears." No seals? Where's the outcry for that? Where's their endangered status? I guess they're not as cute as polar bears.
  37. Did Phil Jones really say global warming ended in 1995?
    Surely one of the most alarming part of the interview was when he(Phil Jones) indicated that he is not very good at keeping records. If one of my students said he had collected some temperature readings but the location of the the readings was uncertain then I would have to disregard them. It should now be obvious that the disputed Chinese readings have to be disregarded.
  38. Is CO2 a pollutant?
    suibhne, replacing all CO2 with N2 would result in much less slowing of the Earth's energy loss to space, because N2 is not a greenhouse gas. Technical explanations are easy to find, but here is a concise one from Wikipedia:
    Although contributing to many other physical and chemical reactions, the major atmospheric constituents, nitrogen (N2), oxygen (O2), and argon (Ar), are not greenhouse gases. This is because molecules containing two atoms of the same element such as N2 and O2 and monatomic molecules such as Ar have no net change in their dipole moment when they vibrate and hence are almost totally unaffected by infrared light.
  39. Increasing CO2 has little to no effect
    Matt, I think I see where your mistaken understanding is coming from. I think you're calculating the spectral radiance from Planck's law (if not, please explain where you get your figure of 180). I get about 150 by my calculations, but that's close enough to demonstrate the problem. The thing is that spectral radiance has a rather complicated definition: energy per unit time per unit surface area per unit solid angle per unit frequency The surface area of the sun is different to the earth - it's about 12000 times greater. 150 times 12000 is actually about 1.8 million. Hence the sun produces about 1.8 million times as much energy at 15 microns. It's hotter and larger, so this shouldn't come as a great surprise. But consider the fact that the sun is radiating this energy out in all directions, and that the earth captures only a tiny proportion of that energy because of our small size. Even Jupiter only appears as a tiny dot in the sky without a telescope. We can work out exactly how much we capture by dividing the area of a circle the size of the earth by the surface area of a sphere at the radius of the earth's orbit: pi*(6400^2)/(4*pi*(150 million)^2) = 0.00000000046 Taking this, and the 1.8 million value found before into account, the earth would (in the absence of atmospheric absorption) radiate out about 1200 times as much energy at 15 microns as we receive from the sun. This isnt true. Visible energy is let in, not heat. The heat of the sun is bloocked by the same GH gasses as block the heat going out. Visible energy IS heat. The heat we get from the sun is mostly within the visible and the near infrared, because the sun is hot and has a blackbody curve centred in the visible. When we absorb it, we radiate it back into space according to a much cooler blackbody spectrum, deeper into the infrared. This is all fairly basic greenhouse theory, and I don't think you've quite grasped the science behind it.
  40. Did Phil Jones really say global warming ended in 1995?
    Oracle2world @41 What you're confirming is that Phil Jones is a straightforward, uncomplicated (and perhaps politically-naive) scientist, rather than a politician with a lawyer's brain. Given that it's agreed by the vast majority of scientists that the world has been on a warming trend since temperature recording began, would it not be totally illogical for Phil Jones to mean, "there has been no warming since 1995"? Clearly, if he thought like a politician, he should NOT have said, 'Yes'; but should have said something like, "It has not been possible to separate a trend from the noise over that period". Surely logic suggests that we must assume that the long term trend continues, given that the noise over the last fifteen years has obscured any statistically-meaningful variation from that temperature trend, either higher or lower?
  41. Is CO2 a pollutant?
    CBDunkerso ...........As to your convection hypothesis... it fails because, amongst other things, greenhouse gases do not retain heat within themselves. They absorb and then immediately re-emit the infrared radiation..... Well surely if the IR radiation is immediately randomly re radiated and all this happens at the speed of light then the time delay introduced by CO2 in a 17Km troposphere would be completely negligible. A thought experiment If co2 were completely absent from the atmosphere and instead we had extra N2 to take their place what THERMAL CHANGE would this produce. (Ignore chemical and biological change for the moment] I have the feeling that the atmosphere would remain much the same.
  42. Arkadiusz Semczyszak at 01:39 AM on 17 February 2010
    Did Phil Jones really say global warming ended in 1995?
    Marcus "One final point, though not statistically significant, temperatures rose by 0.012 degrees per year between 2000 & 2009, yet average sunspot numbers fell by around 14.5 per year." O.K. Cyclical changes in solar activity do not (simple) coincide with the cycle of the Millennium. Agreed. But now we have a typical growth phase temperature in the Millennium cycles in a typical (for him) periods. It was not me saying that this cycle in some way depends on solar activity, and Rahmstorf. In many, many works and commentaries.
  43. Did Phil Jones really say global warming ended in 1995?
    Insofar as you can fit something into a headline, the text "there has been no global warming since 1995" is accurate. Now you can delve into the weeds about significance levels, time periods, datasets, overall trends, caveats, blah, blah, blah ... but the text speaks for itself: BBC: Do you agree that from 1995 to the present there has been no statistically-significant global warming Phil Jones: Yes Now if you want to start adding caveats to ALL global warming headlines ... that would be fine. Like the IPCC in its 2007 report said: "Eleven of the last 12 years rank among the 12 hottest years on record (since 1850, when sufficient worldwide temperature measurements began)." That last parenthetical statement seems to go by the wayside a lot. And maybe a mention of the Medieval Warm Period, and the Holocene maximum would be helpful. And satellite temps versus ground records that omit quite a bit of the earth's surface. Somehow the IPCC infactuation with 12 years of data was important and significant ... but the same years found to be not statistically significant don't really mean much of anything now. Any questions?
  44. The Dunning-Kruger effect and the climate debate
    Oracle2world, your citation of CO2 levels in greenhouses doesn't meet your own criteria for determining whether something is a pollutant or not. To quote, "any substance in excess that is a danger to human health and the natural environment is a pollutant". Greenhouses are demonstrably not the "natural environment". Observed shifts in pH from CO2 increases thus far indicate that humans raising atmospheric CO2 to 1000 ppm would be catastrophic for the oceans of the world... even without the effects of global warming. Ergo, yes... by your own definition CO2 IS a pollutant. As to there being no anomalies in AGW data... there have been plenty. Most (e.g. early UAH satellite temperature series or the first pass of ARGOS buoy ocean heat data) have been due to errors which were later corrected. However, there are some still outstanding... such as calculations of the factors contributing to sea level rise not adding up to the total observed increase. Likewise there is ongoing debate as to the causes of tree ring divergence over the past fifty years and fluctuations in the temperature record (such as the current period of decreased warming). That's not even getting into all the issues around proxies and climate sensitivity... particularly the complexities around clouds having multiple positive AND negative feedback impacts.
  45. Did Phil Jones really say global warming ended in 1995?
    Oops, forgot to include the link. http://sciences.blogs.liberation.fr/files/dix-ans-de-froid-dans-un-si%C3%A8cle-chaud.pdf
  46. Did Phil Jones really say global warming ended in 1995?
    Here's the full text of the Easterling/Wehner paper cited by DIkran Marsupial@24 for JonMoseley@3. DIkran's description:
    "Furthermore, the observed results are in conflict with the predictions of the computer models. Therefore, the computer models are wrong." Actually that is not correct either, see the paper by Easterling and Wehner, which shows that the internal variability of the climate means that there will be occasional decadal trends showing no warming or even cooling, and that these are seen in the output of the models.
  47. The Dunning-Kruger effect and the climate debate
    It would be really good news if people with little scientific training "conformed" to science, scientific consesus and peer review ...
  48. Did Phil Jones really say global warming ended in 1995?
    Regarding the amount of time needed to detect the warming signal against the noise: The statistician Tamino addressed that explicitly in his post How Long?. (That's the same post that Steve L linked to earlier.)
  49. Did Phil Jones really say global warming ended in 1995?
    John/40 Shades, without doing the full statistical analysis we can still use past variability as a general guide. For instance, there was a 30 year 'pause' of mild cooling in the warming trend from ~1940-1970. Thus, the current 15 year period of only mild warming doesn't seem particularly anomalous. For me, it'd have to run more than 30 years (say 40) without warming passing 95% certainty to 'give pause'. That hasn't happened before in the instrumental record so it would indicate something 'new'. Anything shorter than that is just consistent with past variations.
  50. Did Phil Jones really say global warming ended in 1995?
    Ricardo @31 I think you missed the point of '40 Shades of Green's' question. He's (she's?)asking if someone with the required knowledge has done the statistical analysis on the actual data, and what the result was? A fair question I would say. As a lay response I would say there's no magic level of data that must reveal a trend hidden in noise. Imagine looking at a newspaper photograph at a high level of magnification under a microscope: with a few dozen dots (data) visible you wouldn't have a clue what the picture was about. Now reduce the magnification. At a certain point -- and number of dots (data) -- one can start to make out the image and have a stab at what's being revealed. The lower the magnification, the more dots (data) and the more certain you can be of what you're looking at. I hope that helps.

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