tag:blogger.com,1999:blog-9959776.post6710778571567404482..comments2024-02-15T04:42:41.606+00:00Comments on James' Empty Blog: When is the mean better than all models?James Annanhttp://www.blogger.com/profile/04318741813895533700noreply@blogger.comBlogger9125tag:blogger.com,1999:blog-9959776.post-79179304341160752182010-06-28T12:18:50.756+01:002010-06-28T12:18:50.756+01:00Oh this (and associated analysis of the IPCC model...Oh this (and associated analysis of the IPCC models) makes up the bulk of the manuscript - I didn't think the first result was enough to publish by itself, especially as I thought at the time it was pretty widely known.James Annanhttps://www.blogger.com/profile/04318741813895533700noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-18242908347673778292010-06-28T11:12:30.382+01:002010-06-28T11:12:30.382+01:00"Stoat with a rabbit's throat", sure..."Stoat with a rabbit's throat", surely. But thank you for doing this. As far as I can see it looks entirely plausible, and the results seem to fit what one finds for low-dimensions.<br /><br />I actually think this is more interesting than the previous result so I hope you'll pad out your paper with is.William M. Connolleyhttps://www.blogger.com/profile/05836299130680534926noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-47629385621571936912010-06-26T17:39:26.836+01:002010-06-26T17:39:26.836+01:00James You're absolutely right... if the MMM is...James You're absolutely right... if the MMM is exactly centered on the truth, by definition it will to do as well or better than any of the individual models. Oops.Carrickhttps://www.blogger.com/profile/03476050886656768837noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-79521902188771451072010-06-26T10:43:52.345+01:002010-06-26T10:43:52.345+01:00No, the MMM is likely to be better than all models...No, the MMM is likely to be better than all models when the ensemble is truth-centred (or close to it), because the models will be around one standard deviation from the truth but the MMM will be substantially closer. That's what the red lines in the plot show. It also depends on the number of dimensions though.James Annanhttps://www.blogger.com/profile/04318741813895533700noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-3617057971415422122010-06-26T09:14:43.220+01:002010-06-26T09:14:43.220+01:00It seems to me that the MMM will be better than an...It seems to me that the MMM will be better than <i>any</i> of the individual models only when it is not "nearly" centered on truth (I'm thinking the criterion for "nearly" should be a derivable quantity using the framework you've provided). Center it on truth, and you are bound to have some individual models that are better than the MMM.<br /><br />Doesn't that follow from your derived result that:<br /><br />"the squared distance from obs to multi-model mean is less than the mean of the squared distances from the individual models to the obs, by an amount which equals the average of the squared distances from the models to their mean?"Carrickhttps://www.blogger.com/profile/03476050886656768837noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-55412888411098255292010-06-25T21:59:34.043+01:002010-06-25T21:59:34.043+01:00Please don't shatter the earth.
Its the only ...Please don't shatter the earth.<br /><br />Its the only one we have...David B. Bensonhttps://www.blogger.com/profile/02917182411282836875noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-24081846120924780692010-06-25T03:16:35.681+01:002010-06-25T03:16:35.681+01:00You will never be the next Steve McIntyre with tha...You will never be the next Steve McIntyre with that attitudeEliRabetthttps://www.blogger.com/profile/07957002964638398767noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-52187765758462201112010-06-25T00:55:11.570+01:002010-06-25T00:55:11.570+01:00I only really blogged it because people kept askin...I only really blogged it because people kept asking...it should be interesting to those working in the area but not of any earth-shattering significance.James Annanhttps://www.blogger.com/profile/04318741813895533700noreply@blogger.comtag:blogger.com,1999:blog-9959776.post-72885369960723542012010-06-24T16:33:28.190+01:002010-06-24T16:33:28.190+01:00And it is so exciting because you have already con...And it is so exciting because you have already concluded<br /><br />"we find that the CMIP3 ensemble generally provides a rather good sample under the statistically indistinguishable paradigm, although it appears marginally over-dispersive and exhibits some modest biases"<br /><br />Now I wonder whether a different conclusion would be exciting, or make you less inclined to blog about it, or was there some sarcasm about excitment? I think I will go with guessing that it is a very similar or identical conclusion.<br /><br />Distinguishing between overdispersive because of too much weather noise or overdispersive because the trends have too great a variation seems important. I am wondering if comparing MMM to initial condition ensemble means might show different results than comparing MMM to a single individual ensemble members. Does the comparison of both provide additional useful information? Or am I asking silly questions?crandleshttps://www.blogger.com/profile/15181530527401007161noreply@blogger.com