From mboxrd@z Thu Jan 1 00:00:00 1970 X-Spam-Checker-Version: SpamAssassin 3.4.4 (2020-01-24) on polar.synack.me X-Spam-Level: X-Spam-Status: No, score=-1.9 required=5.0 tests=BAYES_00 autolearn=unavailable autolearn_force=no version=3.4.4 Path: eternal-september.org!reader01.eternal-september.org!feeder.eternal-september.org!news.swapon.de!fu-berlin.de!uni-berlin.de!individual.net!not-for-mail From: Niklas Holsti Newsgroups: comp.lang.ada Subject: Re: Not to incite a language war but apparently the Corona lockdown was based on 13 year old undocumented C-Code Date: Wed, 13 May 2020 23:29:09 +0300 Organization: Tidorum Ltd Message-ID: References: Mime-Version: 1.0 Content-Type: text/plain; charset=utf-8; format=flowed Content-Transfer-Encoding: 8bit X-Trace: individual.net gYIJxJRd3byPrUiT6IZ3rAmV3QeFH85HDCa1BNCLUf1SC1RY92 Cancel-Lock: sha1:mT+2I7kkd2lXbyr6iUyDL6zNpw0= User-Agent: Mozilla/5.0 (Macintosh; Intel Mac OS X 10.14; rv:68.0) Gecko/20100101 Thunderbird/68.5.0 In-Reply-To: Content-Language: en-US Xref: reader01.eternal-september.org comp.lang.ada:58683 Date: 2020-05-13T23:29:09+03:00 List-Id: On 2020-05-13 21:58, Optikos wrote: > On Wednesday, May 13, 2020 at 9:05:50 AM UTC-5, Niklas Holsti wrote: >> On 2020-05-13 16:52, Optikos wrote: >>> On Wednesday, May 13, 2020 at 4:36:15 AM UTC-5, Niklas Holsti wrote: >>>> On 2020-05-13 1:39, Jeffrey R. Carter wrote: >>>>> On 5/13/20 12:20 AM, Niklas Holsti wrote: >>>>>> >>>>>> I agree that it would be troubling. If you could find that statement, >>>>>> it would interest me. >>>>> >>>>> In https://lockdownsceptics.org/code-review-of-fergusons-model/ it says, >>>>> "the code produces critically different results, even for identical >>>>> starting seeds and parameters." >>>> >>>> While the review claims that as a general flaw, it then "illustrates" >>>> the claim by discussing the two cases I detailed, in particular the >>>> unexpected influence of the option controlling how the program "stores >>>> data tables". This was eventually traced to a difference in the way the >>>> program used the RNG, depending on this option, which then led to >>>> different PRN sequences, depending on this option. An error in the >>>> program, of course, but not non-determinism. >>>> >>>> For programs that use RNGs to drive simulations, a single extra RNG >>>> call, or a single omitted RNG call, will completely change the >>>> subsequent PRN sequence. This has no effect on the statistical >>>> properties of the results from many runs, but will of course change the >>>> results of the particular run in which the change occurs. >>>> >>>>> Initially it was claimed that this was >>>>> only true for multiple cores, but later that was retracted: "But >>>>> Edinburgh came back and reported that – even in single-threaded mode – >>>>> they still see the problem." >>>> >>>> It seems that some users (Edinburgh) reported that the results varied, >>>> and reported they were using multi-core mode. The authors of the program >>>> (Imperial) replied that result variations are expected in multi-core >>>> mode; this was of course a sloppy analysis of the problem, but not an >>>> unnatural one. When the users reported that the problem occurs also in >>>> single-core mode, depending on the "data table storage" option, the >>>> authors found and fixed the error. >>> >>> On which date did they fix the problem? Before or after governments >>> acted on the miscalculations? >> >> There has been no demonstration that the early predictions from this >> program, that prodded governments into action, were "miscalculations" to >> any significant degree, especially after the recommended practice of >> performing several runs and considering the ensemble of results. > > https://www.cato.org/blog/how-one-model-simulated-22-million-us-deaths-covid-19 In that article, the main objection to Ferguson's model seems to be that the model predicts that as much as 81% of the population would be infected. But the proponents of quick herd immunity suggest something over 60% as desirable, so 81% does not seem outrageous. The article then complains that Ferguson's model is unrealistic because it assumes that no precautions against infection are taken, neither by individuals nor by governments. As I understand it, this assumption was stated and not hidden by Ferguson, so complaining about it is not to the point. Ferguson's point was that precautions *should* be taken to avoid the 2.2 million deaths. > https://www.spectator.co.uk/article/six-questions-that-neil-ferguson-should-be-asked/amp By all means, ask Ferguson such questions, but also let him answer. > 2.2 million deaths in the USA and a half million deaths in the UK > due to Covid-19 [...] were not a miscalculation, but rather a > perfectly accurate calculation. Okey dokey, then. You seem to have misunderstood what we are discussing. The question is if Ferguson's results were influenced by errors (bugs) in Ferguson's code, not if Ferguson's assumptions or mathematical models are realistic or correct for this pandemic. -- Niklas Holsti niklas holsti tidorum fi . @ .