Archive for book review

9 pitfalls of data science [book review]

Posted in Books, Kids, Statistics, Travel, University life with tags , , , , , , , , , , , , , on September 11, 2019 by xi'an

I received The 9 pitfalls of data science by Gary Smith [who has written a significant number of general public books on personal investment, statistics and AIs] and Jay Cordes from OUP for review a few weeks ago and read it on my trip to Salzburg. This short book contains a lot of anecdotes and what I would qualify of small talk on job experiences and colleagues’ idiosyncrasies…. More fundamentally, it reads as a sequence of examples of bad or misused statistics, as many general public books on statistics do, but with little to say on how to spot such misuses of statistics. Its title (It seems like the 9 pitfalls of… is a rather common début for a book title!) however started a (short) conversation with my neighbour on the train to Salzburg as she wanted to know if the job opportunities in data sciences were better in Germany than in Austria. A practically important question for which I had no clue. And I do not think the book would have helped either! (My neighbour in the earlier plane to München had a book on growing lotus, which was not particularly enticing for launching a conversation either.)

Chapter I “Using bad data” is made of examples of truncated or cherry picked data often associated with poor graphics. Only one dimensional outcome and also very US centric. Chapter II “Data before theory” highlights spurious correlations and post hoc predictions, criticism of data mining, some examples being quite standard. Chapter III “Worshiping maths” sounds like the perfect opposite of the previous cahpter: it discusses the fact that all models are wrong but some may be more wrong than others. And gives examples of over fitting, p-value hacking, regression applied to longitudinal data. With the message that (maths) assumptions are handy and helpful but not always realistic. Chapter IV “Worshiping computers” is about the new golden calf and contains rather standard stuff on trusting the computer output because it is a machine. However, the book is somewhat falling foul of the same mistake by trusting a Monte Carlo simulation of a shortfall probability for retirees since Monte Carlo also depends on a model! Computer simulations may be fine for Bingo night or poker tournaments but much more uncertain for complex decisions like retirement investments. It is also missing the biasing aspects in constructing recidivism prediction models pointed out in Weapons of math destruction. Until Chapter 9 at least. The chapter is also mentioning adversarial attacks if not GANs (!). Chapter V “Torturing data” mentions famous cheaters like Wansink of the bottomless bowl and pizza papers and contains more about p-hacking and reproducibility. Chapter VI “Fooling yourself” is a rather weak chapter in my opinion. Apart from Ioannidis take on Theranos’ lack of scientific backing, it spends quite a lot of space on stories about poker gains in the unregulated era of online poker, with boasts of significant gains that are possibly earned from compulsive gamblers playing their family savings, which is not particularly praiseworthy. And about Brazilian jiu-jitsu. Chapter VII “Correlation vs causation” predictably mentions Judea Pearl (whose book of why I just could not finish after reading one rant too many about statisticians being unable to get causality right! Especially after discussing the book with Andrew.). But not so much to gather from the chapter, which could have instead delved into deep learning and its ways to avoid overfitting. The first example of this chapter is more about confusing conditionals (what is conditional on what?) than turning causation around. Chapter VII “Regression to the mean” sees Galton’s quincunx reappearing here after Pearl’s book where I learned (and checked with Steve Stiegler) that the device was indeed intended for that purpose of illustrating regression to the mean. While the attractive fallacy is worth pointing out there are much worse abuses of regression that could be presented. CHANCE’s Howard Wainer also makes an appearance along SAT scores. Chapter IX “Doing harm” does engage into the issue that predicting social features like recidivism by a (black box) software is highly worrying (and just plain wrong) if only because of this black box nature. Moving predictably to chess and go with the right comment that this does not say much about real data problems. A word of warning about DNA testing containing very little about ancestry, if only because of the company limited and biased database. With further calls for data privacy and a rather useless entry on North Korea. Chapter X “The Great Recession“, which discusses the subprime scandal (as in Stewart’s book), contains a set of (mostly superfluous) equations from Samuelson’s paper (supposed to scare or impress the reader?!) leading to the rather obvious result that the expected concave utility of a weighted average of iid positive rvs is maximal when all the weights are equal, result that is criticised by laughing at the assumption of iid-ness in the case of mortgages. Along with those who bought exotic derivatives whose construction they could not understand. The (short) chapter keeps going through all the (a posteriori) obvious ingredients for a financial disaster to link them to most of the nine pitfalls. Except the second about data before theory, because there was no data, only theory with no connection with reality. This final chapter is rather enjoyable, if coming after the facts. And containing this altogether unnecessary mathematical entry. [Usual warning: this review or a revised version of it is likely to appear in CHANCE, in my book reviews column.]

Japan’s Kumano Kodo pilgrimage [book review]

Posted in Books, Mountains, Running, Travel with tags , , , , , , , , , , , , on September 8, 2019 by xi'an

When preparing our hiking trip to the Kumano Kodo pilgrimage route, I was extremely pleased to find a dedicated guidebook that covered precisely the region we wanted to explore and provided enough background material to make the walk sound feasible. However, once I found the Kumano Travel reservation website, run most efficiently by the Tanabe City Kumano Tourism Bureau, the information contained in this site made the guidebook less relevant. And when we arrived in Tanabe at the start of the trail, I found that the Bureau was also distributing free leaflets in English for each of the three main routes, which described day-by-day the stages of the hikes, as well as recommendations and tips. Making in the end or a posteriori the guidebook superfluous. (As the detailed description of the routes was not necessary, given how clearly they are identified. The leaflet managed to stand the five days on the trail despite rain, humidity, frequent consultations and a general lack of care, as shown above!)  Hence, while there is nothing wrong with the guidebook which also includes an extra day-hike along the Eastern coast of the Kii peninsula and another one from Koyasan to the bottom of the cablecar [again covered by leaflets at the local tourism bureau], I would not strongly recommend it. Interestingly (?), when I stated these mere facts as a review on Amazon, I was rejected as contravening their review guidelines without further precision… (I can only post comments on the French portal of Amazon as my associate gains mean that I never “buy” anything on the US portal!)


the (forty-)seven samurai (赤穂浪士)

Posted in Books, pictures, Travel with tags , , , , , , , , , , , , , , on August 25, 2019 by xi'an

During my vacations in Japan, I read the massive (1096p) book by Osaragi Jiro on the  Akō incident, with occidental title the 47 rōnins. Which I had bought in Paris before leaving. This is a romancized version of an historical event that took part in 1701 in the Genroku era. Where 47 rōnin (leaderless samurai) avenged the death of their former master Takumi no Kami ordered by the current Shôgun after Takumi no Kami stuck an official Kira Yoshinaka who had insulted him publicly. And were also condemned to commit sepuku. (As I suspected while reading the book, it was initially published in 1927-1928 as a series, which explains for its length.) This is a very famous story in the Japanese culture and there exist many versions in novels, plays, movies, one featuring the fabulous Toshirō Mifune (and another one commissioned by the Japanese military during WWII), and prints, including some by Hiroshige and Hokusai. Not only it is a great read, with a very classical style (in the French translation) and enough plots and subplots to deserve the 1096 pages!, but it also reflects [much more than in Yoshikawa’s Musashi] upon the transition from feudal to modern Japan, with the samurai class slowly dwindling out for the merchant class and a central administration. Which the central characters in the book mostly bemoan and hence praise the chivaleresque action of the 47 rōnins, fighting against superior forces, except for some who reflect on the uselessness of a warrior class (and go as far as assassinating random samurai). Interestingly, the conclusion of the real story, namely the suicide of the 47 rōnins, is not included in the book. Which links the head of the revenge to famous characters of the time, including a scholar anticipating the Meiji rise of Japanese nationalism by removing cultural and religious links to China, including the preeminence of Shintoism over Buddhism. The book is also the attention paid to seasons and gardens throughout, which is a feature I found in many Japanese books. Somewhat unsurprisingly, the story involves very few female central characters and, except for one spy, very passive roles.

el lector de cadaveres [book review]

Posted in Books with tags , , , , , , on August 20, 2019 by xi'an

lelecteur-decadavres El lector de cadaveres (the corpse reader) by Antonio Garrido (from Valencià) is an historical novel I picked before departing to Japan as the cover reminded me of van Gulik’s Judge Dee which I very enjoy9788467013849ed (until a terrible movie came out!). Although van Gulik apparently took the idea from a 18th-century Chinese detective crime novel Di Gong An. Anyway, this seemed like a good travel book, although heavy in my hiking backpack. After reading it mostly in the trains, I am not so convinced that it was a great idea! The story stemmed from the author attending a legal medecine conference in Mumbai and hearing of a 13th century Chinese medical expert who could be the very first forensic doctor. The book builds upon this historical character, romancing his early life from destitute to becoming the legal medicine expert of the Song emperor. There are a lot of similarities with Judge Dee in that the meritocratic structure of the Chinese government is central to the central character joining the academy and postulating for the imperial examinations. That the underworld is never far from the ruling classes. That superstition is also a permanent feature in everyday’s life. That cruelty is a part of justice as well as an intricate legal code. And that confucianism is strictly ruling the society, from top to bottom. The historical part is rather nice, with a higher degree of details and apparent authenticity than van Gulik’s. This shows the research undertaken by the author was quite fruitful. The plot however is terrible, with Song Ci falling in every possible trap, trusting every villain in the vicinity and shooting himself in the foot at every occasion. The story goes from one disaster to the next, Ci being only saved by a last minute benevolent passerby. His brilliance as a forensic officer is hard to explain when considering the stupidity he demonstrates all along, while the novel involves several others who also work on the medical analysis of corpses for the courts. A very lengthy suspension of belief!

blackwing [book review]

Posted in Books, pictures with tags , , , , , , , , , on August 10, 2019 by xi'an

Another fantasy series of the gritty type, maybe not up to the level of the first ground-breaking Abercrombie’s but definitely great!  With some reminiscence of Lawrence’s first series but with a better defined and more complex universe and a not so repulsive central character. Maybe even not repulsive at all when considered past and current actions as described from his perspective…

“I’ve run the equations on it. It took me two days to plot them. Bear in mind that this is far, far beyond any light matrix that I’ve seen calculated before.”

The whole book is indeed written from Captain Ryhalt‘s viewpoint. A bounty hunter for a post- and pre-apocalyptic society, returning fugitives’ head to the central authorities but governed by a Nameless deity on top of everything (?). Appearing as a raven, hence the compelling cover, hence me buying the book! The plot is unraveling at such a pace that it keeps the tension going, especially since it is rather unpredictable. As noted above, it creates a fairly original universe and while magic is heavily involved, there are limitations to the powers of the sorcerers, witches,  half-gods and other entities that mean no deus-ex-machina last minute resolution, sort of. Actually (spoiler alert!) the machine at the core of the story is not doing too well… With repeated mentions made of mathematics governing the handling of the machine, including one over-the-top computation on the ceiling of a cell! It is only when I finished the book that I realised this was part of a series, as the story could have ended there. (Maybe should have, if the associated reviews for the next two volumes are to be trusted.)

prime suspects [book review]

Posted in Books, Kids, University life with tags , , , , , , , , , , , , , , on August 6, 2019 by xi'an

I was contacted by Princeton University Press to comment on the comic book/graphic novel Prime Suspects (The Anatomy of Integers and Permutations), by Andrew Granville (mathematician) & Jennifer Granville (writer), and Robert Lewis (illustrator), and they sent me the book. I am not a big fan of graphic book entries to mathematical even less than to statistical notions (Logicomix being sort of an exception for its historical perspective and nice drawing style) and this book did nothing to change my perspective on the subject. First, the plot is mostly a pretense at introducing number theory concepts and I found it hard to follow it for more than a few pages. The [noires maths] story is that “forensic maths” detectives are looking at murders that connects prime integers and permutations… The ensuing NCIS-style investigation gives the authors the opportunity to skim through the whole cenacle of number theorists, plus a few other mathematicians, who appear as more or less central characters. Even illusory ones like Nicolas Bourbaki. And Alexander Grothendieck as a recluse and clairvoyant hermit [who in real life did not live in a Pyrénées cavern!!!]. Second, I [and nor is Andrew who was in my office when the book arrived!] am not particularly enjoying the drawings or the page composition or the colours of this graphic novel, especially because I find the characters drawn quite inconsistently from one strip to the next, to the point of being unrecognisable, and, if it matters, hardly resembling their real-world equivalent (as seen in the portrait of Persi Diaconis). To be completely honest, the drawings look both ugly and very conventional to me, in that I do not find much of a characteristic style to them. To contemplate what Jacques TardiFrançois Schuiten or José Muñoz could have achieved with the same material… (Or even Edmond Baudoin, who drew the strips for the graphic novels he coauthored with Cédric Villani.) The graphic novel (with a prime 181 pages) is postfaced with explanations about the true persons behind the characters, from Carl Friedriech Gauß to Terry Tao, and of course on the mathematical theory for the analogies between the prime and cycles frequencies behind the story. Which I find much more interesting and readable, obviously. (With a surprise appearance of Kingman’s coalescent!) But also somewhat self-defeating in that so much has to be explained on the side for the links between the story, the characters and the background heavily loaded with “obscure references” to make sense to more than a few mathematician readers. Who may prove to be the core readership of this book.

There is also a bit of a Gödel-Escher-and-Bach flavour in that a piece by Robert Schneider called Réverie in Prime Time Signature is included, while an Escher’s infinite stairway appears in one page, not far from what looks like Milano Vittorio Emmanuelle gallery (On the side, I am puzzled by the footnote on p.208 that “I should clarify that selecting a random permutation and a random prime, as described, can be done easily, quickly, and correctly”. This may be connected to the fact that the description of Bach’s algorithm provided therein is incomplete.)

[Disclaimer about potential self-plagiarism: this post or an edited version will eventually appear in my Books Review section in CHANCE. As appropriate for a book about Chance!]

the grey bastards [book review]

Posted in Books with tags , , , , , , on July 21, 2019 by xi'an

Another almost random read, The Grey Bastards by Jonathan French is a light (if gritty) fantasy book that should appeal to Warhammer players. Including the use of hogs as mounts. In that the main characters are half-orcs, in a Universe where lots of species (also found in Warhammer) co-exist, if not peacefully. The idea of reverting the usual perspective on orcs as dumb killers was already found in Stan Nicholls’ Orcs, which I found better than the current Grey Bastards, especially because there is not much to distinguish these from humans, sentiments included, apart from their appearance, but this makes for an enjoyable travel read. Since the characters are rather well-drawn, the story is rather (too?) simple and one can see where it is heading. (Some reviews commented on the Tolkien-meets-Sons-of-Anarchy aspect of the book, but as I have not watched the series…) There is at least one central weakness to the plot that I will not reveal, which first comes as a great shocker but is then later explained by a rather lame arm bending blackmail, that makes the story not as strong as it could have been. Upon finishing the book I found out that (a) there was a second book in the series about to appear and (b) it has won the 2016 Self-published fantasy blog-off prize, a prize started by Mark Lawrence (author of Red Sister) to “shine a light on self-published fantasy” which sounds like a great idea, in that it helps the authors towards commercial publishing. The jury is made of 10  fantasy bloggers going through a rather time-consuming process.