Archive for book review

Mördar-Anders och hans vänner [book review]

Posted in Books, Travel with tags , , , , , , , , on February 25, 2017 by xi'an

“The medieval city of Visby and its shops were preparing for the approaching Christmas season. Interest rates were down to 0.0, which encouraged people to spend money they did not have so that Christmas sales would break records once again.” (p.332)

Thanks to these forced 24 hours in Schiphol, I bought and read a third book by the Swedish author Jonas Jonasson. Which title is Hitman Anders and the meaning of it all. The themes are almost exactly the same as in the previous novels, namely an improbable bunch of losers, growing like a dustball during the story, being unexpectedly provided (like the hundred-year old man) with a huge sum of money by illegal means and managing to keep it from the reach of the State and of a whole collection of gangsters, with a bit of a road movie outside Stockholm and the same fascination for camper-vans [without an elephant this time] and some mild reflections on the role of religion in Swedish society. Plus the customary appearance of the King and Queen. Not absolutely unpleasant but not superlatively funny and somewhat repetitive. (Like the 20th novel of Paasilinna!)

a concise introduction to statistical inference [book review]

Posted in Statistics with tags , , , , , , , , , , on February 16, 2017 by xi'an

[Just to warn readers and avoid emails about Xi’an plagiarising Christian!, this book was sent to me by CRC Press for a review. To be published in CHANCE.]

This is an introduction to statistical inference. And with 180 pages, it indeed is concise! I could actually stop the review at this point as a concise review of a concise introduction to statistical inference, as I do not find much originality in this introduction, intended for “mathematically sophisticated first-time student of statistics”. Although sophistication is in the eye of the sophist, of course, as this book has margin symbols in the guise of integrals to warn of section using “differential or integral calculus” and a remark that the book is still accessible without calculus… (Integral calculus as in Riemann integrals, not Lebesgue integrals, mind you!) It even includes appendices with the Greek alphabet, summation notations, and exponential/logarithms.

“In statistics we often bypass the probability model altogether and simply specify the random variable directly. In fact, there is a result (that we won’t cover in detail) that tells us that, for any random variable, we can find an appropriate probability model.” (p.17)

Given its limited mathematical requirements, the book does not get very far in the probabilistic background of statistics methods, which makes the corresponding chapter not particularly helpful as opposed to a prerequisite on probability basics. Since not much can be proven without “all that complicated stuff about for any ε>0” (p.29). And makes defining correctly notions like the Central Limit Theorem impossible. For instance, Chebychev’s inequality comes within a list of admitted results. There is no major mistake in the chapter, even though mentioning that two correlated Normal variables are jointly Normal (p.27) is inexact.

“The power of a test is the probability that you do not reject a null that is in fact correct.” (p.120)

Most of the book follows the same pattern as other textbooks at that level, covering inference on a mean and a probability, confidence intervals, hypothesis testing, p-values, and linear regression. With some words of caution about the interpretation of p-values. (And the unfortunate inversion of the interpretation of power above.) Even mentioning the Cult [of Significance] I reviewed a while ago.

Given all that, the final chapter comes as a surprise, being about Bayesian inference! Which should make me rejoice, obviously, but I remain skeptical of introducing the concept to readers with so little mathematical background. And hence a very shaky understanding of a notion like conditional distributions. (Which reminds me of repeated occurrences on X validated when newcomers hope to bypass textbooks and courses to grasp the meaning of posteriors and such. Like when asking why Bayes Theorem does not apply for expectations.) I can feel the enthusiasm of the author for this perspective and it may diffuse to some readers, but apart from being aware of the approach, I wonder how much they carry away from this brief (decent) exposure. The chapter borrows from Lee (2012, 4th edition) and from Berger (1985) for the decision-theoretic part. The limitations of the exercise are shown for hypothesis testing (or comparison) by the need to restrict the parameter space to two possible values. And for decision making. Similarly, introducing improper priors and the likelihood principle [distinguished there from the law of likelihood] is likely to get over the head of most readers and clashes with the level of the previous chapters. (And I do not think this is the most efficient way to argue in favour of a Bayesian approach to the problem of statistical inference: I have now dropped all references to the likelihood principle from my lectures. Not because of the controversy, but simply because the students do not get it.) By the end of the chapter, it is unclear a neophyte would be able to spell out how one could specify a prior for one of the problems processed in the earlier chapters. The appendix on de Finetti’s formalism on personal probabilities is very much unlikely to help in this regard. While it sounds so far beyond the level of the remainder of the book.

sex, lies, & brain scans [not a book review]

Posted in Statistics with tags , , , , , , , on February 11, 2017 by xi'an

“Sahakian and Gottwald discuss the problem of “reverse inference” regrettably late in the book.”

In the book review section of Nature [Jan 12, 2017 issue], there was a long coverage of the book sex. lies, & brain scans: How fMRI Reveals What Really Goes on in our Minds, by Barbara J. Sahakian and Julia Gottwald. While I have not read the book (which is not even yet out on amazon), I found some mentions of associating brain patterns with criminal behaviour quite puzzling: “neuroimaging will probably be an imperfect predictor of criminal behaviour”. Actually, much more than puzzling, both frightening with its Minority Report prospects [once again quoted as a movie rather than Philip K. Dick’s novel!], and bordering the irrational, for associating breaking rules with a brain pattern. Of course this is just an impression from reading a book review and the attempts may be restricted to psychological diseases rather than attempt at social engineering and brain policing, but if this is the case, as suggested by the review, it is downright scary!

the three-body problem [book review]

Posted in Books with tags , , , , , , , on February 5, 2017 by xi'an

“Back then, I thought of one thing: Have you heard of the Monte Carlo method? Ah, it’s a computer algorithm often used for calculating the area of irregular shapes. Specifically, the software puts the figure of interest in a figure of known area, such as a circle, and randomly strikes it with many tiny balls, never targeting the same spot twice. After a large number of balls, the proportion of balls that fall within the irregular shape compared to the total number of balls used to hit the circle will yield the area of the shape. Of course, the smaller the balls used, the more accurate the result.

Although the method is simple, it shows how, mathematically, random brute force can overcome precise logic. It’s a numerical approach that uses quantity to derive quality. This is my strategy for solving the three-body problem. I study the system moment by moment. At each moment, the spheres’ motion vectors can combine in infinite ways. I treat each combination like a life form. The key is to set up some rules: which combinations of motion vectors are “healthy” and “beneficial,” and which combinations are “detrimental” and “harmful.” The former receive a survival advantage while the latter are disfavored. The computation proceeds by eliminating the disadvantaged and preserving the advantaged. The final combination that survives is the correct prediction for the system’s next configuration, the next moment in time.”

While I had read rather negative reviews of the Three-Body Problem, I still decided to buy the book from an Oxford bookstore and give it a try. Ìf only because this was Chinese science-fiction and I had never read any Chinese science-fiction. (Of course the same motivation would apply for most other countries!) While the historical (or pseudo-historical) part of the novel is most interesting, about the daughter of a university physicist killed by Red Guards during the Cultural Revolution and hence forever suspect, even after decades of exile, the science-fiction part about contacting another inhabited planet and embracing its alien values based on its sole existence is quite deficient and/or very old-fashioned. As is [old-fashioned] the call to more than three dimensions to manage anything, from space travel to instantaneous transfer of information, to ultimate weapons. And an alien civilization that is not dramatically alien. As for the three body problem itself, there is very little of interest in the book and the above quote on using Monte Carlo to “solve” the three-body problem is not of any novelty since it started in the early 1940’s.

I am thus very much surprised at the book getting a Hugo award. For a style that is more reminiscent of early Weird Tales than of current science-fiction… In addition, the characters are rather flat and often act in unnatural ways. (Some critics blame the translation, but I think it gets deeper than that.)

The Cairo Affair [book review]

Posted in Statistics with tags , , , , , , , , , , on January 28, 2017 by xi'an

After reading the Tourist trilogy, I decided to embark upon another spy novel by Steinhauer and took this book to India as another “emergency” book. Meaning as a way to escape delays and waits during our travel. While this is not a major change from the above trilogy, which I really liked, The Cairo Affair reads well and thus fits its purpose. Some of the appeal of the book is its immersion in very recent geopolitical events in Libya (far from over by now) and Egypt. (I presume there are a lot of other spy novels taking advantage of these major shifts, so this is not a major incentive for the book!) Another appeal is the connection with places I visited as a (real) tourist, from Budapest, to Croatia, to Cairo, even though I got a much more fragmented picture of the latter in the few days I spent there. While the underlying plot ends up being very thin (spoiler?!), I also liked the extreme ambiguity of the main character, whose motivations are never really revealed, possibly unknown even to herself. This major aspect of the novel makes for shortcomings on the realism plane. Worth a plane ride, definitely.

la maison des mathématiques

Posted in Books, Kids, pictures, Statistics, University life with tags , , , , , , , , on January 14, 2017 by xi'an

ihp0When I  worked with Jean-Michel Marin at Institut Henri Poincaré the week before Xmas, there was this framed picture standing on the ground, possibly in preparation for exhibition in the Institute. I found this superposition of the lady cleaning the blackboard from its maths formulas and of the seemingly unaware mathematician both compelling visually in the sheer geometric aesthetics of the act and somewhat appalling in its message. Especially when considering the initiatives taken by IHP towards reducing the gender gap in maths. After inquiring into the issue, I found that this picture was part of a whole photograph exhibit on IHP by Vincent Moncorgé, now published into a book, La Maison des Mathématiques by Villani, Uzan, and Moncorgé. Most pictures are on-line and I found them quite appealing. Except again for the above.

Great North Road [book review]

Posted in Books, Running, Travel with tags , , , , , , , , , , , , , , , on January 6, 2017 by xi'an

As I was unsure of the Internet connections and of the more than likely delays I would face during my trip to India, I went fishing for a massive novel on Amazon and eventually ordered Peter Hamilton’s Great North Road, a 1088 pages behemoth! I fear the book qualifies as space opera, with the conventional load of planet invasions, incomprehensible and infinitely wise aliens, gateways for instantaneous space travels, and sentient biospheres. But the core of the story is very, very, Earth-bound, with a detective story taking place in a future Newcastle that is not so distant from now in many ways. (Or even from the past as the 2012 book did not forecast Brexit…) With an occurrence of the town moor where I went running a few years ago.

The book is mostly well-designed, with a plot gripping enough to keep me hooked for Indian evenings in Kolkata and most of the flight back. I actually finished it just before landing in Paris. There is no true depth in the story, though, and the science fiction part is rather lame: a very long part of the detective plot is spent on the hunt for a taxi by an army of detectives, a task one would think should be delegated to a machine-learning algorithm and solved in a nano-second or so. The themes heavily borrow from those of classics like Avatar, Speaker for the Dead, Hyperion [very much Hyperion!], Alien… And from The Girl with the Dragon Tattoo for an hardcore heroin who is perfect at anything she undertakes.  Furthermore, the Earth at the centre of this extended universe is very close to its present version, with English style taxis, pub culture, and a geopolitic structure of the World pretty much unchanged. Plus main brands identical to currents ones (Apple, BMW, &tc), to the point it sounds like sponsored links! And no clue of a major climate change despite the continued use of fuel engines. Nonetheless, an easy read when stuck in an airport or a plane seat for several hours.