Archive for Bruxelles

piano tuners on France Inter

Posted in Kids, University life, Books with tags , , , , , , , , , , , on August 14, 2026 by xi'an

During the summer months, the Belgian physicist Fabrizio Bucella delivers a daily and funny unit of wisdom every morning just before 8am (CET) on the French public radio. Often addressing every day question to uncover a scientific principle. A recent morn, he mentioned Fermi’s estimates, which is a numerate way to guess(timate) a physical quantity by multiplying individual estimates, like the number of piano tuners in Chicago. (My preparatory school physics teacher was very good at this game, beating our pocket calculators by a large margin!) But I had never heard either of the concept or of the expression. Bucella’s 2mn explanation was quite similar to the Wikipedia entry, if not mentioning that the squared root increase of the error applies to the logarithm of the estimate. And arguing unreasonably at all terms being above or below their true values with probability ½. The paradox of the waiting time the day after was more convincing, if failing to mention Siméon Poisson. [The above is a picture I took of Lake Michigan while running, the last time I visited Chicago. A few days before Barack Obama got re-elected.]

a journal of the chaos (en cuisine) year

Posted in Books, Kids, Mountains, pictures, Travel, Wines with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on June 12, 2025 by xi'an

 Read La Fille du Grand Hiver (The Daughter of the Great Winter) by Isabelle Autissier (also a sailor who was the first woman to complete a solo world race in 1991). This is a novelised version of the story of Arnarulunguaq, who accompanied Knud Rasmussen on the Fifth Thule Expedition over several years, all the way to the Bering Strait. She died of tuberculosis the year after. (And will appear on a Dane banknote soon.) The novel is told from Arnarulunguaq‘s perspective, as she opens to wider possibilities, cultural diversity, and traces back her Inuit lineage along Knud Rasmussen. It is a beautiful travel story (and then some more), in the fascinating Far North, which further reminded me of a catholic missionary visiting our primary school in the mid  1960’s and giving a conference on the Inuits and their culture. I pressed my parents until they bought his book and read it over and over, probably the seed of my fascination for the Far North!

Mis-made both a vat of rice pudding—presumably by first grinding the rice grains as the whey did not get absorbed—and a vat of chocolate mousse!—by not melting the chocolate long enough—and another of vegan mousse—by failing to notice the chickpea water was salted and that my MIL’s egg-beater was broken (but I salvaged it into a decent mole, if not with 49 ingredients)! I also grilled panned hot chilis I had found on a local market, but they were so hot they made me cough and open all windows; they are now resting in an olive oil jar, to be soon tested!!! Rhubarb is back in the stalls of my local market, providing me with my breakfast spread for the coming weeks. I again enjoyed Toukoul’s dora wat on the night of the privaCI workshopt—a workshop that focussed almost entirely on contextual integrity, if with very little overlap with the BIRS workshop in Kelowna. And harvested as many cherries as possible from our fruitful (!) cherry tree (#1) before the local birds are them all.

Watched Black Doves, with (Bend it Like Beckham) Keira Knightley as the only recognisable actress in the set, a very cartoony spies series taking place in London at Xmas time, with funny dialogues and too good vibes that should restrict a viewer to watching the show on 24 December and no other day.

The 7th Annual PrivaCI Symposium, 19-20 May, Brussels

Posted in pictures, Statistics, University life with tags , , , , , , , , , , , , , , on January 24, 2025 by xi'an

at the boor, as advertised

Posted in pictures, Statistics with tags , , , , , , , , , , , , , , , , on March 8, 2024 by xi'an

Number savvy [book review]

Posted in Books, Statistics with tags , , , , , , , , , , , , , , , , , , , , , , , , , , , , , on March 31, 2023 by xi'an

“This book aspires to contribute to overall numeracy through a tour de force presentation of the production, use, and evolution of data.”

Number Savvy: From the Invention of Numbers to the Future of Data is written by George Sciadas, a  statistician working at Statistics Canada. This book is mostly about data, even though it starts with the “compulsory” tour of the invention(s) of numbers and the evolution towards a mostly universal system and the issue of measurements (with a funny if illogical/anti-geographical confusion in “gare du midi in Paris and gare du Nord in Brussels” since Gare du Midi (south) is in Brussels while Gare du Nord (north) in in Paris). The chapter (Chap. 3) on census and demography is quite detailed about the hurdles preventing an exact count of a population, but much less about the methods employed to improve the estimation. (The request for me to fill the short form for the 2023 French Census actually came while I was reading the book!)

The next chapter links measurement with socio-economic notions or models, like unemployment rate, which depends on so many criteria (pp. 77-87) that its measurement sounds impossible or arbitrary. Almost as arbitrary as the reported number of protesters in a French demonstration! Same difficulty with the GDP, whose interpretation seems beyond the grasp of the common reader. And does not cover significantly missing (-not-at-random) data like tax evasion, money laundering, and the grey economy. (Nitpicking: if GDP got down by 0.5% one year and up by 0.5% the year after, this does not exactly compensate!) Chapter 5 reflects upon the importance of definitions and boundaries in creating official statistics and categorical data. A chapter (Chap 6) on the gathering of data in the past (read prior to the “Big Data” explosion) is preparing the ground to the chapter on the current setting. Mostly about surveys, presented as definitely from the past, “shadows of their old selves”. And with anecdotes reminding me of my only experience as a survey interviewer (on Xmas practices!). About administrative data, progressively moving from collected by design to available for any prospection (or “farming”). A short chapter compared with the one (Chap 7) on new data (types), mostly customer, private sector, data. Covering the data accumulated by big tech companies, but not particularly illuminating (with bar-room remarks like “Facebook users tend to portray their lives as they would like them to be. Google searches may reflect more truthfully what people are looking for.”)

The following Chapter 8 is somehow confusing in its defence of microdata, by which I understand keeping the raw data rather than averaging through summary statistics. Synthetic data is mentioned there, but without reference to a reference model, while machine learning makes a very brief appearance (p.222). In Chapter 9, (statistical) data analysis is [at last!] examined, but mostly through descriptive statistics. Except for a regression model and a discussion of the issues around hypothesis testing and Bayesian testing making its unique visit, albeit confusedly in-between references to Taleb’s Black swan, Gödel’s incompleteness theorem (which always seem to fascinate authors of general public science books!), and Kahneman and Tversky’s prospect theory. Somewhat surprisingly, the chapter also includes a Taoist tale about the farmer getting in turns lucky and unlucky… A tale that was already used in What are the chances? that I reviewed two years ago. As this is a very established parable dating back at least to the 2nd century B.C., there is no copyright involved, but what are the chances the story finds its way that quickly in another book?!

The last and final chapter is about the future, unsurprisingly. With prediction of “plenty of black boxes“, “statistical lawlessness“, “data pooling” and data as a commodity (which relates with some themes of our OCEAN ERC-Synergy grant). Although the solution favoured by the author is centralised, through a (national) statistics office or another “trusted third party“. The last section is about the predicted end of theory, since “simply looking at data can reveal patterns“, but resisting the prophets of doom and idealising the Rise of the (AI) machines… The lyrical conclusion that “With both production consolidation and use of data increasingly in the ‘hands’ of machines, and our wise interventions, the more distant future will bring complete integrations” sounds too much like Brave New World for my taste!

“…the privacy argument is weak, if not hypocritical. Logically, it’s hard to fathom what data that we share with an online retailer or a delivery company we wouldn’t share with others (…) A naysayer will say nay.” (p.190)

The way the book reads and unrolls is somewhat puzzling to this reader, as it sounds like a sequence of common sense remarks with a Guesstimation flavour on the side, and tiny historical or technical facts, some unknown and most of no interest to me, while lacking in the larger picture. For instance, the long-winded tale on evaluating the cumulated size of a neighbourhood lawns (p.34-38) does not seem to be getting anywhere. The inclusion of so many warnings, misgivings, and alternatives in the collection and definition of data may have the counter-effect of discouraging readers from making sense of numeric concepts and trusting the conclusions of data-based analyses. The constant switch in perspective(s) and the apparent absence of definite conclusions are also exhausting. Furthermore, I feel that the author and his rosy prospects are repeatedly minimizing the risks of data collection on individual privacy and freedom, when presenting the platforms as a solution to a real time census (as, e.g., p.178), as exemplified by the high social control exercised by some number savvy dictatures!  And he is highly critical of EU regulations such as GDPR, “less-than-subtle” (p.267), “with its huge impact on businesses” (p.268). I am thus overall uncertain which audience this book will eventually reach.

[Disclaimer about potential self-plagiarism: this post or an edited version will potentially appear in my Books Review section in CHANCE.]