Archive for American football

a journal of the conquest, war, famine, death[s], and chaos year

Posted in Books, Kids, Mountains, pictures, Running, Travel with tags , , , , , , , , , , , , , , , , , , , , , , , , , , on April 10, 2024 by xi'an

Read John Scalzi’s Head On, which is set in the same future America as Lock In, involving again the Halden syndrome patients forced to live by remotely operating robots (threeps) and introducing an extreme form of American football adapted to these patients, since they cannot be injured when their threep is. (Not as in the terrible 1975 dystopic Rollerball, which was supposedly taking place in… 2018!). The two main FBI detectives are the same as in Lock In, with great and funny dialogues but with mostly dialogues!, and a surprising disregard for team work and reporting to their hierarchy. My conclusion of the review of Lock In thus stands:

“the Halden detective conveniently happens to be the son of a very influential ex-basketball-player and hence to meet all the characters involved in the plot. This is pleasant but somewhat thin with a limited number of players considering the issues at stake and a rather artificial ending.”

Starting to cook a matcha rice pudding as an experiment, which proved successful in keeping both the matcha taste ad the rice pudding texture, and in lowering considerably the input of sugar [from which I must shy] in the recipe. (In all honesty, I actually used an organic substitute to matcha, grown and made in China!)

Found out while going to a repair shop for a brake replacement that my second bike (the one that I can leave locked in the street for a few hours!) was in such a bad state that I should not drive it. The wheels had indeed lost most of their material at the level of the brakes, due to alien, abrasive, material getting stuck inside the brake pads. My nearby repair shop was clearly uninterested in repairing a cheap, ten year old, bike and gave me a quote that was larger than my original purchase amount. I thus found a Décathlon store nearby PariSanté campus and brought back a new wheel attached to my backpack, which proved more manageable than dreaded!

Watched in the nearby cinema A Man (ある男) by Kei Ishikawa, based on a book with the same title by Keiichiro Hirano, that won the Yomiuri Prize for Literature.  (The main actress Sakura Ando also played a central role in the fantastic Cannes Palme d’Or winner Shoplifters.) I went thinking it would be a psychological thriller, but it proved me wrong, as the movie is much more about self identity, intimacy, and societal prejudices, than a detective story about usurped identity. The pace is deliberately slow and the director light, impressionist, touch gives depth and freedom to the characters, while keeping some of the mysteries behind the story open. I really enjoyed the film, which was the first time I had returned to a cinema since watching a Jim Harrison documentary in 2022. I also discovered thanks to the beginning and final scenes an infinitely deep René Magritte’s painting, La Reproduction Interdite, which I had never seen, and which was a perfect still for the film message.

Leave a comment »

Who’s #1?

Posted in Books, Kids, Statistics, University life with tags , , , , , , , , , , , , , , , on May 2, 2012 by xi'an

First, apologies for this teaser of a title! This post is not about who is #1 in whatever category you can think of, from statisticians to climbs [the Eiger Nordwand, to be sure!], to runners (Gebrselassie?), to books… (My daughter simply said “c’est moi!” when she saw the cover of this book on my desk.) So this is in fact a book review of…a book with this catching title I received a month or so ago!

“We decided to forgo purely statistical methodology, which is probably a disappointment to the hardcore statisticians.” A.N. Langville & C.D. Meyer, Who’s #1? The Science of Rating and Ranking (page 225)

This book may be one of the most boring ones I have had to review so far! The reason for this disgruntled introduction to “Who’s #1? The Science of Rating and Ranking” by Langville and Meyer is that it has very little if any to do with statistics and modelling. (And also that it is mostly about American football, a sport I am not even remotely interested in.) The purpose of the book is to present ways of building rating and ranking within a population, based on pairwise numerical connections between some members of this population. The methods abound, at least eight are covered by the book, but they all suffer from the same drawback that they are connected to no grand truth, to no parameter from an underlying probabilistic model, to no loss function that would measure the impact of a “wrong” rating. (The closer it comes to this is when discussing spread betting in Chapter 9.) It is thus a collection of transformation rules, from matrices to ratings. I find this the more disappointing in that there exists a branch of statistics called ranking and selection that specializes in this kind of problems and that statistics in sports is a quite active branch of our profession, witness the numerous books by Jim Albert. (Not to mention Efron’s analysis of baseball data in the 70’s.)

“First suppose that in some absolutely perfect universe there is a perfect rating vector.” A.N. Langville & C.D. Meyer, Who’s #1? The Science of Rating and Ranking (page 117)

The style of the book is disconcerting at first, and then some, as it sounds written partly from Internet excerpts (at least for most of the pictures) and partly from local student dissertations… The mathematical level is highly varying, in that the authors take the pain to define what a matrix is (page 33), only to jump to Perron-Frobenius theorem a few pages later (page 36). It also mentions Laplace’s succession rule (only justified as a shrinkage towards the center, i.e. away from 0 and 1), the Sinkhorn-Knopp theorem, the traveling salesman problem, Arrow and Condorcet, relaxation and evolutionary optimization, and even Kendall’s and Spearman’s rank tests (Chapter 16), even though no statistical model is involved. (Nothing as terrible as the completely inappropriate use of Spearman’s rho coefficient in one of Belfiglio’s studies…)

“Since it is hard to say which ranking is better, our point here is simply that different methods can produce vastly different rankings.” A.N. Langville & C.D. Meyer, Who’s #1? The Science of Rating and Ranking (page 78)

I also find irritating the association of “science” with “rating”, because the techniques presented in this book are simply tricks to turn pairwise comparison into a general ordering of a population, nothing to do with uncovering ruling principles explaining the difference between the individuals. Since there is no validation for one ordering against another, we can see no rationality in proposing any of those, except to set a convention. The fascination of the authors for the Markov chain approach to the ranking problem is difficult to fathom as the underlying structure is not dynamical (there is not evolving ranking along games in this book) and the Markov transition matrix is just constructed to derive a stationary distribution, inducing a particular “Markov” ranking.

“The Elo rating system is the epitome of simple elegance.” A.N. Langville & C.D. Meyer, Who’s #1? The Science of Rating and Ranking (page 64)

An interesting input of the book is its description of the Elo ranking system used in chess, of which I did not know anything apart from its existence. Once again, there is a high degree of arbitrariness in the construction of the ranking, whose sole goal is to provide a convention upon which most people agree. A convention, mind, not a representation of truth! (This chapter contains a section on the Social Network movie, where a character writes a logistic transform on a window, missing the exponent. This should remind Andrew of someone he often refer to in his blog!)

“Perhaps the largest lesson is not to put an undue amount of faith in anyone’s rating.” A.N. Langville & C.D. Meyer, Who’s #1? The Science of Rating and Ranking (page 125)

In conclusion, I see little point in suggesting reading this book, unless one is interested in matrix optimization problems and/or illustrations in American football… Or unless one wishes to write a statistics book on the topic!

3 Comments »