tag:blogger.com,1999:blog-9959776.post2353557052545108764..comments2024-02-15T04:42:41.606+00:00Comments on James' Empty Blog: Probabilistic Forecasting - A PrimerJames Annanhttp://www.blogger.com/profile/04318741813895533700noreply@blogger.comBlogger7125tag:blogger.com,1999:blog-9959776.post-1070814805650554142011-08-21T05:58:09.866+01:002011-08-21T05:58:09.866+01:00Must be some software problem over at Blog Pielke;...Must be some software problem over at Blog Pielke; trying to select a userid then preview a response seems to just blank the comment field. Repeated multiple tries.Hank Robertshttps://www.blogger.com/profile/07521410755553979665noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-76407597593384498282011-08-20T02:23:44.866+01:002011-08-20T02:23:44.866+01:00So what is the probability of Roger not posting a ...So what is the probability of Roger not posting a comment that points to this post? Eli did an experiment early this afternoon, and as of 9:22 it looks like the house won.<br /><br />It's this sort of childish behavior that makes him such a delight.EliRabetthttps://www.blogger.com/profile/07957002964638398767noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-50066632789888409892011-08-19T18:37:39.167+01:002011-08-19T18:37:39.167+01:00He seems to be, at the very least, a dishonest bro...He seems to be, at the very least, a dishonest broker, with his sleight-of-hand meta-statistic spin?Carl Chttps://www.blogger.com/profile/14717209873111026574noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-66087327544568804662011-08-19T02:30:42.000+01:002011-08-19T02:30:42.000+01:00The only thing that is clear so far is that Roger ...The only thing that is clear so far is that Roger is completely confused and his approach is incoherent. In his latest he appears to accept that a prediction may be wrong even when the event turns out precisely in agreement with it (non-appearance of an asteroid). He seems to think that rhetoric and sophistry can overcome simple mathematics.James Annanhttps://www.blogger.com/profile/04318741813895533700noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-74668698418149050002011-08-18T10:42:49.939+01:002011-08-18T10:42:49.939+01:00This gives a rather clear explanation of probabili...This gives a rather clear explanation of probabilistic climate predictions:<br /><br />http://ukclimateprojections.defra.gov.uk/content/view/1989/500/<br /><br />“It is very important to understand what a probability means in UKCP09. The interpretation of probability generally falls into two broad categories. The first type of probability relates to the expected frequency of occurrence of some outcome, over a large number of independent trials carried out under the same conditions: for example the chance of getting a five (or any other number) when rolling a dice is 1 in 6, that is, a probability of about 17%. This is not the meaning of the probabilities supplied in UKCP09, as there can only be one pathway of future climate. In UKCP09, we use the second type (called Bayesian probability) where probability is a measure of the degree to which a particular level of future climate change is consistent with the information used in the analysis, that is, the evidence. In UKCP09, this information comes from observations and outputs from a number of climate models, all with their associated uncertainties. The methodology which allows us to generate probabilities is based on large numbers (ensembles) of climate model simulations, but adjusted according to how well different simulations fit historical climate observations in order to make them relevant to the real world. The user can give more consideration to climate change outcomes that are more consistent with the evidence, as measured by the probabilities. Hence, Figure 8(a) does not say that the temperature rise will be less than 2.3ºC in 10% of future climates, because there will be only one future climate; rather it says that we are 10% certain (based on data, current understanding and chosen methodology) that the temperature rise will be less than 2.3ºC. One important consequence of the definition of probability used in UKCP09 is that the probabilistic projections are themselves uncertain, because they are dependent on the information used and how the methodology is formulated.”<br /><br />Which makes me think of Richard Tol’s comment over at Rogers:<br /><br />“Roger and James are both right. Roger is right if one assumes that the IPCC predicts events, James is right if one assumes that the IPCC predicts probability density functions.”<br /><br />Could it be that the argument is really about what the IPCC actually predicts?<br /><br />This also relates to the difference in the IPCC lingo between likelihood and confidence. Another hornet’s nest. It seems that the quote by Doswell and Brookes conflates the two where it says that “It simply means that one is more certain of the event than the other.” Being (un)certain relates to confidence; not likelihood (in IPCC lingo at least). It’s rather blurry at this point though and perhaps I’m utterly confused here.<br /><br />The title of Roger’s initial post is still entirely off-base of course, no matter how you slice it.Bart Verheggenhttps://www.blogger.com/profile/12409420404605117255noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-26818909937364576402011-08-18T04:37:59.236+01:002011-08-18T04:37:59.236+01:00What the hell? He wants to make a beef with the I...What the hell? He wants to make a beef with the IPCC with statements like:<br /><br /><b><br />That is why evaluation of probabilistic statements is necessary. <br /></b><br /><br />while refusing to admit his own problems with statements <a href="http://rogerpielkejr.blogspot.com/2011/07/making-stuff-up-at-real-climate.html" rel="nofollow"> here. </a><br /><br />Me:<br /><b><br />The issue is that neither the 30% or the 50% projections has any basis in physical reality. Read what James Annan and other were trying to tell you 3 years ago. And then you used those invalid boundary parameters to question basic conclusions of the science community. So, of course, when it turns out that the invalid projections were wrong, it is going to be pointed out. A simple admission that these were wrong would suffice, I'm sure. <br /></b><br /><br />And finalizes the argument by telling me <br /><br /><b><br />More importantly you seem to gloss over the entire point of the sensitivity analysis exercise, which is to explore the sensitivity of conclusions to assumptions, not to predict a single 'right' conclusion. In this case the need to revisit the IPCC conclusion is insensitive to whether the community accepts a surface temperature change of 50%, 30% or 15% -- the implications are robust to such uncertainties.<br /></b>Anonymousnoreply@blogger.comtag:blogger.com,1999:blog-9959776.post-28527642087108986412011-08-18T03:39:41.584+01:002011-08-18T03:39:41.584+01:00As I previously wrote,
42.As I previously wrote,<br /><br />42.David B. Bensonhttps://www.blogger.com/profile/02917182411282836875noreply@blogger.com