Archive for Nate Silver

coronavirus counts do not count

Posted in Books, pictures, Statistics with tags , , , , , , , , on April 8, 2020 by xi'an

Somewhat by chance I came across Nate Silver‘s tribune on FiveThirtyEight about the meaninglessness of COVID-19 case counts. As it reflects on sampling efforts and available resources rather than actual cases, furthermore sampling efforts from at least a fortnight.

“The data, at best, is highly incomplete, and often the tip of the iceberg for much larger problems. And data on tests and the number of reported cases is highly nonrandom. In many parts of the world today, health authorities are still trying to triage the situation with a limited number of tests available. Their goal in testing is often to allocate scarce medical care to the patients who most need it — rather than to create a comprehensive dataset for epidemiologists and statisticians to study.”

This article runs four different scenarios, with the same actual parameters for the epidemics, and highly different and mostly misleading perceptions based on the testing strategies. This is a highly relevant warning but I am surprised Nate Silver does not move to the rather obvious conclusion that some form of official survey or another, for instance based on capture-recapture and representative samples, testing for present and past infections, should be implemented on a very regular basis, even with a limited number of tested persons to get a much more reliable vision of the status of the epidemics. Here, the French official institute of statistics, INSEE, would be most suited to implement such a scheme.

“In short, the French presidential election is a mess”

Posted in Statistics with tags , , , , , , on April 23, 2017 by xi'an

Harry Enten (and not Nate Silver as reported by Le Monde) published yesterday a post on Five-Thirty-Eight about the unpredictability of the French elections. Which essentially states the obvious, namely that the four major candidates all stand a chance to make it to the runoff. (The post classifies Macron as a former left-wing socialist, which shows a glaring misunderstanding of the candidate or a massive divergence of what left-wing means between France and the USA.) The tribune states both that the polls could exhibit a bigger mistake than in the previous elections and that Le Pen score is unlikely to be underestimated, because voters are no longer shy to acknowledge they vote for a fascist candidate. One argument for the error in the polls is attributed to pollsters “herding” their results, i.e., shrinking the raw figures towards the global average taken over previous polls. A [rather reasonable] correction dismissed by Le Monde and French pollsters. While Enten argues that the variability of the percentages over fifty polls is too small to be plausible, assuming a Normal distribution that may not hold because French pollsters use quotas to build their polling population. In any case, this analysis, while cautious and reasonably so!, does not elaborate on the largest question mark, the elephant in the room, namely the percentage of abstentions today and their distribution among the political spectrum, which may eventually make the difference tonight. Indeed, “the bottom line is that we don’t know what’s going to happen on Sunday.” And it is definitely frightening!


Posted in Books, Kids, pictures with tags , , on January 1, 2017 by xi'an

I find this xkcd entry very much in tune with my own feelings and misgivings about 2017. I like the notion that 2016 is sending us in the future without things (and people) it would have been better to keep. Like reaching out instead of building barriers, whether about staying in the EU or uniting all Americans under one’s presidency, rather than tweeting scorn, exclusion, and righteousness. Like keeping hospitals standing and operating, instead of flattening them out, in Syria, Irak, Yemen and Afghanistan. Like preserving women’s access to contraception and abortion, instead of [old men] ruling over their body and rights. No, 2017 does not look too promising.

xkcd [interview & book]

Posted in Books, Kids, Statistics with tags , , , , , , , on September 14, 2014 by xi'an

Of interest for xkcd fans: What If?: Serious Scientific Answers to Absurd Hypothetical Questions is out! Actually, it is currently the #1 bestseller on amazon! (A physics book makes it to the top of the bestseller list, a few weeks after a theoretical economics book got there. Nice! Actually, a statistics book also made it to the top: Nate Silver’s The SIgnal and the Noise….) I did not read the book, but it is made of some of the questions answered by Randall Munroe (the father of xkcd) on his what if blog. In connection with this publication, Randall Munroe is interviewed on FiveThirtyEight (Nate Silver’s website), as kindly pointed out to me by Bill Jefferys. The main message is trying to give people a feeling about numbers, a rough sense of numeracy. Which was also the purpose of the guesstimation books.

Scottish polls…

Posted in pictures, Statistics, Travel with tags , , , , , , , , on September 11, 2014 by xi'an

Hillhead Street from the Great Western Road, Glasgow westside, Apr. 20, 2012As much as I love Scotland, or because of it, I would not dream of suggesting to Scots that one side of the referendum sounds better than the other. However, I am rather annoyed at the yoyo-like reactions to the successive polls about the result, because, just like during the US elections, each poll is analysed separately rather than being pooled with the earlier ones in a reasonable meta-analysis… Where is Nate Silver when we need him?!