# Posts

### April 21, 2015

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2:11 AM | The Mozart Myth

I don’t know how many times I’ve heard about how Mozart would compose entire musical scores in his head and only write them down once they were finished. Even authors who stress that creativity requires false starts and hard work have said that Mozart may have been an exception. But maybe he wasn’t. In his new book How to […]

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Suppose you have a polynomial-time algorithm that operates on sets of weighted elements, and involves comparisons of the weights of different sets. (This describes many different algorithms for shortest paths, minimum spanning trees, minimum weight matchings, closures, etc.) But suppose also that your algorithm is only guaranteed to work correctly when different sets always have distinct total weights. When comparisons could come out equal, your algorithm could crash or produce incorrect […]

### April 20, 2015

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This early morning, just before going out for my daily run around The Parc, I checked X validated for new questions and came upon that one. Namely, how to simulate X a Bin(8,2/3) variate and Y a Bin(18,2/3) such that corr(X,Y)=0.5. (No reason or motivation provided for this constraint.) And I thought the following (presumably […]

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8:48 PM | Pedantic arithmetic rules

Generations of math teachers have drilled into their students that they must reduce fractions. That serves some purpose in the early years, but somewhere along the way students need to learn reducing fractions is not only unnecessary, but can be bad for communication. For example, if the fraction 45/365 comes up in the discussion of […]

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5:00 PM | In Praise of Fractals and Poetry

This year for Math Poetry month, I read Proportions of the Heart: Poems that Play with Mathematics, a collection of poems by Emily Grosholz. Grosholz is both a philosophy professor at Penn State and...
-- Read more on ScientificAmerican.com

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Fränzi and Tobias‘s book is now real: Fränzi Korner-Nievergelt, Tobias Roth, Stefanie von Felten, Jérôme Guélat, Bettina Almasi, and Pius Korner-Nievergelt (2015) Bayesian Data Analysis in Ecology Using Linear Models with R, BUGS, and Stan. Academic Press. This is based in part on the in-person tutorials that they and the other authors have been giving […]
The post New Book: Bayesian Data Analysis in Ecology Using Linear Models with R, BUGS, and Stan
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1:00 PM | On deck this week

Mon: New book on Bayesian analysis in ecology using Stan Tues: The feather, the bathroom scale, and the kangaroo Wed: Instead of worrying about multiple hypothesis correction, just fit a hierarchical model. Thurs: Political Attitudes in Social Environments Fri: Statistical significance, practical significance, and interactions Sat: Statistical analysis on a dataset that consists of a […]
The post On deck this week appeared first on Statistical Modeling, Causal Inference, and Social
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Dal 18 al 20 aprile si sono svolte le finali delle Olimpiadi italiane dell'astronomia, con la cerimonia della premiazione avvenuta quest'oggi. Stefano Sandrelli, presidente del comitato olimpico, ha pubblicato su twitter le foto dei vincitori per le due categorie junior e senior. Eccoli qui sotto, contenti per il riconoscimento ottenuto grazie al loro studio:I 5 junior vincitor #olimpiadiastronomia @mediainaf pic.twitter.com/m05eLkcr9h— stefano sandrelli (@stefacrono) April 20, 2015I
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US organisations the Mathematical Sciences Research Institute (MSRI) and the Children’s Book Council (CBC) have founded a youth book prize, called Mathical: Books for Kids from Tots to Teens. The prizes, awarded for the first time this year, recognise the most inspiring maths-related fiction and nonfiction books aimed at young people. This year, they’ve awarded a set... Read more »

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The Euler equations for three-dimensional incompressible inviscid fluid flow are where is the velocity field, and is the pressure field. For the purposes of this post, we will ignore all issues of decay or regularity of the fields in question, assuming that they are as smooth and rapidly decreasing as needed to justify all the […]

### April 19, 2015

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10:15 PM | Bayesian propaganda?

“The question is about frequentist approach. Bayesian is admissable only by wrong definition as it starts with the assumption that the prior is the correct pre-information. James-Stein beats OLS without assumptions. If there is an admissable [sic] frequentist estimator then it will correspond to a true objective prior.” I had a wee bit of a […]

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I like it. Clear, transparent, no mumbo jumbo about their secret sauce. But . . . what’s with the hyper-precision: C’mon. “27.4%”? Who are you kidding?? (See here for explication of this point.)
The post Go to PredictWise for forecast probabilities of events in the news appeared first on Statistical Modeling, Causal Inference, and Social Science.

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12:18 PM | sakura

Filed under: pictures, Running, Travel Tagged: cherry blossom, cherry tree, Japanese traditions, morning light, morning run, Parc de Sceaux, Paris suburbs, sakura

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1:21 AM | Diederik Stapel in the news, again

Bikes . . . have “become the most common mode of transportation for criminals.” OK, that’s just ethnic profiling of Dutch people. I think they’re just gonna put the whole country on lockdown.
The post Diederik Stapel in the news, again appeared first on Statistical Modeling, Causal Inference, and Social Science.

### April 18, 2015

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11:37 PM | Leonard Euler

This week we celebrated Euler’s birthday on 15th and I thought I need to write something about him. In my (almost) 4 years of university I have heard his name a lot of time. And this is a thing especially because at most of my courses the teachers don’t say anything about the mathematicians that […]

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10:15 PM | Amsterdamse huizen

Filed under: pictures, Running, Travel, University life Tagged: Amsterdam, architecture, coffeehouse, Holland

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Readers, Aunt Pythia has an amazing guest philosopher here with her today in sunny Berkeley, a paradise on earth and home to the Kouign Amann: His name is Aristippus, and he claims to be the inventor of hedonism. We’ll be the judges of that, though, shall we? His philosophy dictates a lifestyle in which he […]

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3:15 PM | #thatlogicproblem round-up

C: $K_A m; \\ K_B d.$ A: $\neg K_A d; \\ m \vDash \neg K_B m.$ B: $d \not\vDash K_B m; \\ (K_A(\neg K_B m)) \vDash K_B (m,d).$ A: $m \wedge K_B(m,d) \vDash K_A (m,d).$ Albert, Bernard and Cheryl have had a busy week. They’re the stars of #thatlogicproblem, a question from a Singapore maths test... Read more »

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2:06 PM | L'odore della polvere calda

Il giocatore di Planescape: Torment interpreta un personaggio che si risveglia su un pianeta sconosciuto senza alcuna memoria sulla sua identità o sui suoi ricordi. Le missioni che il videogioco gli proporrà saranno un percorso per recuperare i ricordi perduti. E' la stessa situazione in cui si trova Verloc, che si sveglia con immagini confuse nella testa mentre un gorilla robotico che fuma un sigaro, Churchill, gli viene incontro contento che sia sopravvissuto a una ignota […]

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I was talking with someone today about various “dead on arrival” research programs we’ve been discussing here for the past few years: I’m talking about topics such beauty and sex ratios of children, or ovulation and voting, or ESP—all of which possibly represent real phenomena and could possibly be studied in a productive way, just […]
The post How do data and experiments fit into a scientific research program? appeared first on Statistical Modeling, Causal
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In June 2013, NSA contractor Edward Snowden met with journalists Glenn Greenwald and Ewen Macaskill and film-maker Laura Poitras in Hong Kong. The whistleblower gave them documents which proved the existence of a massive scale surveillance system that allows the American NSA and other intelligence and security agencies to gather information on citizens without judicial supervision. While in the USA and in Germany the major media outlets reported extensively on the issue, in Italy there hasn't
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### April 17, 2015

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10:15 PM | the luminaries [book review]

I bought this book by Eleanor Catton on my trip to Pittsburgh and Toronto in 2013 (thanks to Amazon associates’ gains!), mostly by chance (and also because it was the most recent Man Booker Prize). After a few sleepless nights last week (when I should not have been suffering from New York jet lag!, given […]

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9:34 PM | Le masse che fanno la differenza

La differenza di massa tra neutrone e protone è decisamente molto piccola. Le ultime notizie la danno a circa 2.53 volte la massa dell'elettrone, che è qualcosa come poco più di 0.5 MeV. Questa differenza di massa tra le due particelle nucleari è fondamentale per il nostro universo: esso, infatti, sarebbe profondamente diverso da come appare se, per esempio, questa differenza fosse di circa un terzo del valore attuale, ovvero di poco inferiore alla massa
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Wilczek F. (2015). Particle physics: A weighty mass difference, Nature, 520 (7547) 303-304. DOI: http://dx.doi.org/10.1038/nature14381

Borsanyi S., Durr S., Fodor Z., Hoelbling C., Katz S.D., Krieg S., Lellouch L., Lippert T., Portelli A., Szabo K.K. & Toth B.C. (2015). Ab initio calculation of the neutron-proton mass difference, Science, 347 (6229) 1452-1455. DOI: http://dx.doi.org/10.1126/science.1257050

Lenz F. (1951). The Ratio of Proton and Electron Masses, Physical Review, 82 (4) 554-554. DOI: http://dx.doi.org/10.1103/physrev.82.554.2

Citation

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If you are going to write about something, especially if you intend to lay bare somebody else’s ignorance, it pays to actually know what you are talking about otherwise you could well end up looking like a total idiot, as … Continue reading →

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I sent my post about the political implication of behavioral economics, embodied cognition, etc., to Gerd Gigerenzer, who commented as follows: The “half-empty” versus “half-full” explanation of the differences between Kahneman and us misses the essential point: the difference is about the nature of the glass of rationality, not the level of the water. For […]
The post Gigerenzer on logical rationality vs. ecological rationality appeared first on Statistical
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I’m on record complaining about how journalists dumb down stories in blind pursuit of “naming the victim” or otherwise putting a picture on the story. But then again, sometimes that’s exactly what you need to do, especially when the story is super complicated. Case in point: the Snowden revelations story. In the past 2 weeks I’ve seen the […]

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12:18 PM | Amsterdam XXX [very hot]

Filed under: pictures, Running, Travel Tagged: Amsterdam, boat, Holland, Java-eiland, Nieuwendammerham, North Sea, sunrise

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7:16 AM | The red door

I couldn't resist photographing this door to a lecture hall in the science sector of the UCI campus. I'm not sure what the pink paint brushmarks are: vandalism? Rustoleum? But they make a nice pattern.( Another shot of the same door )

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1:08 AM | Parametric closures

My latest arXiv preprint, The Parametric Closure Problem (arXiv:1504.04073, to appear at WADS) concerns an old optimization problem that can be used, among other applications, in the planning process for open-pit mining.Suppose you have the mining rights to a three-dimensional patch of earth and rock, in which the ore is of a type and depth that make it appropriate to remove the ore by digging down to it from above rather than by tunneling. You can make a three-dimensional model of your mining
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