Archive for Vietnam

counting COVID-19 deaths (or not)

Posted in Statistics with tags , , , , , , , , , , , on September 7, 2020 by xi'an

Two COVID-19 articles in the recent issue of Nature relating to data gathering issues. One on the difficulty to distinguish direct COVID deaths from indirect ones from the excess deaths, which “to many scientists, it’s the most robust way to gauge the impact of the pandemic” (which I supported). As indeed the COVID pandemic reduced people access to health care, both because health structures were overwhelmed and because people were scared of catching the virus when visiting these structures. The article [by Giuliana Viglione] supports the direct exploitation of death certificates, to improve the separation, quoting Natalie Dean from the University of Florida in Gainesville. Although this creates a strong lag in the reporting and hence in health policy decisions. (Assuming the overall death reporting is to be trusted, which is not the case for all countries.)

“This long-standing neglect has been exacerbated by the lack of national leadership during the pandemic.”

The other article is about the reasons why the COVID-19 crisis in the US is doubled by a COVID-19 data crisis. Mentioning “political meddling, privacy concerns and years of neglect of public-health surveillance systems” as some of the sources for unreliable data on the pandemic range and evolution. Hardly any contact tracking (as opposed to South Korea or Vietnam), a wealth of local, state and federal structures, data diverted and hence delayed (or worse) to a new system launched by the US Department for Health and Human Services (HHS) for an ill-used $10 million. And data often shared (or lost) by fax! “Lack of leadership,” to state the obvious….

Covid’s game-of-life

Posted in Books, pictures, Travel, University life with tags , , , , , , , on May 7, 2020 by xi'an

A colleague from Paris Dauphine, Miquel Oliu-Barton made a proposal in Le Monde for an easing of quarantine that sounds somehow like Conway’s game of life. The notion is to define a partition of the country into geographical zones with green versus red labels, representing the absence versus presence of contagious individuals. With weekly updates depending on the observed cases or the absence thereof. While this is a nice construct that can be processed as a game theory problem, I am not so sure that it fits the specific dynamics of the coronavirus, which is not immediately detected while active, hence inducing a loss of efficiency in returning quickly enough to a red status. Not mentioning the unreliability and unavailability of tests at this scale. Or an open society (as opposed to China or Vietnam) where (a) people will resent local lockdown more than they do with global lockdown and (b) mostly operate outside the box for work or family interactions.

another viral math puzzle

Posted in Books, Kids, R, University life with tags , , , , , , , on May 25, 2015 by xi'an

After the Singapore Maths Olympiad birthday problem that went viral, here is a Vietnamese primary school puzzle that made the frontline in The Guardian. The question is: Fill the empty slots with all integers from 1 to 9 for the equality to hold. In other words, find a,b,c,d,e,f,g,h,i such that

a+13xb:c+d+12xef-11+gxh:i-10=66.

With presumably the operation ordering corresponding to

a+(13xb:c)+d+(12xe)f-11+(gxh:i)-10=66

although this is not specified in the question. Which amounts to

a+(13xb:c)+d+(12xe)f+(gxh:i)=87

and implies that c divides b and i divides gxh. Rather than pursing this analytical quest further, I resorted to R coding, checking by brute force whether or not a given sequence was working.

baoloc=function(ord=sample(1:9)){
if (ord[1]+(13*ord[2]/ord[3])+ord[4]+
12*ord[5]-ord[6]-11+(ord[7]*ord[8]/
ord[9])-10==66) return(ord)}

I then applied this function to all permutations of {1,…,9} [with the help of the perm(combinat) R function] and found the 128 distinct solutions. Including some for which b:c is not an integer. (Not of this obviously gives a hint as to how a 8-year old could solve the puzzle.)

As pointed out in a comment below, using the test == on scalars is a bad idea—once realising some fractions may be other than integers—and I should thus replace the equality with an alternative that bypasses divisions,

baoloc=function(ord=sample(1:9)){
return(((ord[1]+ord[4]+12*ord[5]-ord[6]-87)*
ord[3]*ord[9]+13*ord[2]*ord[9]+
ord[3]*ord[7]*ord[8]==0)*ord)}

leading to the overall R code

sol=NULL
perms=as.matrix(data.frame(permutations(9)),ncol=9,byrow=TRUE)
for (t in 1:factorial(9)){
  a=baoloc(perms[t,])
  if (a[1]>0) sol=rbind(sol,a)}
sol=sol[do.call(order, as.data.frame(sol)),]

and returning the 136 different solutions…

the forever war [book review]

Posted in Books, Kids with tags , , , , , on April 26, 2015 by xi'an

Another book I bought somewhat on a whim, although I cannot remember which one… The latest edition has a preface by John Scalzi, author of Old Man’s War and its sequels, where he acknowledged he would not have written this series, had he previously read The Forever War. Which strikes me as ironical as I found Scalzi’s novels way better. Deeper. And obviously not getting obsolete so immediately! (As an aside, Scalzi is returning to the Old Man’s War universe with a new novel, The End of All Things.)

“…it’s easy to compute your chances of being able to fight it out for ten years. It comes to about two one-thousandths of one percent. Or, to put it another way, get an old-fashioned six-shooter and play Russian Roulette with four of the six chambers loaded. If you can do it ten times in a row without decorating the opposite wall, congratulations! You’re a civilian.”

This may be the main issue with The Forever War. The fact that it sounds so antiquated. And hence makes reading the novel like an exercise in Creative Writing 101, in order to spot how the author was so rooted in the 1970’s that he could not project far enough in the future to make his novel sustainable. The main issue in the suspension of belief required to proceed through the book is the low-tech configuration of Halderman’s future. Even though intergalactic travel is possible via the traditional portals found in almost every sci’-fi’ book, computers are blatantly missing from the picture. And so is artificial intelligence as well. (2001 A space odyssey was made in 1968, right?!) The economics of a forever warring Earth are quite vague and unconvincing. There is no clever tactics in the war against the Taurans. Even the battle scenes are far from exciting. Esp. the parts where they fight with swords and arrows. And the treatment of sexuality has not aged well. So all that remains in favour of the story (and presumably made the success of the book) is the description of the ground soldier’s life which could almost transcribe verbatim to another war and another era. End of the story. (Unsurprisingly, while being the first book picked for the SF MasterworksThe Forever War did not make it into the 2011 series…)

snapshot from my SIOD 2013 talk

Posted in pictures, Statistics, Travel, University life with tags , , , , , on July 11, 2013 by xi'an