Posts

October 26, 2014

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3:30 AM | Stem cells, branching processes and stochasticity in cancer
When you were born, you probably had 270 bones in your body. Unless you’ve experienced some very drastic traumas, and assuming that you are fully grown, then you probably have 206 bones now. Much like the number and types of internal organs, we can call this question of science solved. Unfortunately, it isn’t always helpful […]

Traulsen, A., Pacheco, J. & Dingli, D. (2010). Reproductive fitness advantage of BCR–ABL expressing leukemia cells, Cancer Letters, 294 (1) 43-48. DOI: 10.1016/j.canlet.2010.01.020

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October 25, 2014

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2:03 PM | 1. Produce defective cars 2. ? 3. Double profit!
“Profit Doubles at G.M., as It Strives to Move Past Its Litany of Recalls”: General Motors’ quarterly earnings report on Thursday was noteworthy mostly for what it lacked: another big financial charge for safety recalls. After running up special charges of nearly $3 billion in the first half of the year for safety problems, G.M., […]
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11:43 AM | Aunt Pythia’s advice
You guys know how much Aunt Pythia loves you, right (answer: a ton)? OK, good. Because that means I can be honest with you. The truth is, I’ve been getting some very weird questions recently, and I’ve had to throw out a bunch of them, sifting through the weeds to find some tulips. It’s not […]
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1:09 AM | How well does sample range estimate range?
I’ve been doing some work with Focused Objective lately, and today the following question came up in our discussion. If you’re sampling from a uniform distribution, how many samples do you need before your sample range has an even chance of covering 90% of the population range? This is a variation on a problem I’ve […]

October 24, 2014

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10:14 PM | Rivers of London [book review]
Yet another book I grabbed on impulse while in Birmingham last month. And which had been waiting for me on a shelf of my office in Warwick. Another buy I do not regret! Rivers of London is delightful, as much for taking place in all corners of London as for the story itself. Not mentioning […]
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10:08 PM | Hong Kong Elementary School First Grade Student Admission Test Question
What parking spot number is the car parked in? Share:
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9:25 PM | Silas Johnson on weighted discriminants with mass formulas
My Ph.D. student Silas Johnson just posted his thesis paper to the arXiv, and it’s cool, and I’m going to blog about it! How should you count number fields?  The most natural way is by discriminant; you count all degree-n number fields K with a given Galois group G in S_n and discriminant bounded in […]
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7:46 PM | Information and Structure in Complex Systems
Eight years ago, I had finished my first year of graduate school in math, and I was at a loss as to what to research.  My original focus, differential geometry, was a beautiful subject to learn about, but the open research questions were too abstract and technical to sustain my interest.  I wanted something more relevant to the real world, something I could talk to people about.Looking for new ideas, I took a course in complex systems, run by the New England Complex Systems […]
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7:46 PM | Information and Structure in Complex Systems
Eight years ago, I had finished my first year of graduate school in math, and I was at a loss as to what to research.  My original focus, differential geometry, was a beautiful subject to learn about, but the open research questions were too abstract and technical to sustain my interest.  I wanted something more relevant to the real world, something I could talk to people about.Looking for new ideas, I took a course in complex systems, run by the New England Complex Systems […]
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4:25 PM | Pokemon Fractals
If you are following my Facebook page, you probably already know my love for Fractals. The math behind these is not as easy as expected, but the result is extremely beautiful. In case you don’t know what a fractal is … Continue reading →
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1:14 PM | Solution to the helicopter design problem
See yesterday’s post for background. Here’s the question: In the helicopter activity, pairs of students design paper ”helicopters” and compete to create the copter that takes longest to reach the ground when dropped from a fixed height. The two parameters of the helicopter, a and b, correspond to the length of certain cuts in the […] The post Solution to the helicopter design problem appeared first on Statistical Modeling, Causal Inference, and Social Science.
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10:33 AM | The class warfare of Halloween
What’s the best thing about Halloween, the dress-up or the candy? Or is it the fact that, for that one night, you can go up to people’s houses and ring their bell and talk to them when they answer the door, and if you’re a kid you can even get demand and receive a gift? […]
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10:01 AM | L'Italia che vince!
E' un periodo che, per vari motivi, mi perdo informazioni. Per fortuna ci sono e-mail e newsletter che informano, e così accade anche per i risultati della spedizione italiana alle Olimpiadi Internazionali dell'Astronomia che dal Kirghizistan, sede della competizione, tornano con tre medaglie, un oro e due bronzi, festeggiati persino da Samantha Cristoforetti su twitter. Veniamo, però, al comunicato stampa inviatomi da Stefano Sandrelli:Sono tre, i premi vinti quest'anno dalla […]
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3:42 AM | Is the two-Burke ballot the new butterfly ballot?
Scott Walker’s opponent takes on the WEDC: BURKE:  One other area outside of that that people really should take a look at is the Wisconsin Economic Development Corporation, which was a nonprofit, public-private corporation created in 2011 which Governor Walker used to make himself the chair of. What’s most interesting is that Governor Walker’s experience […]

October 23, 2014

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10:14 PM | Feller’s shoes and Rasmus’ socks [well, Karl's actually...]
Yesterday, Rasmus Bååth [of puppies' fame!] posted a very nice blog using ABC to derive the posterior distribution of the total number of socks in the laundry when only pulling out orphan socks and no pair at all in the first eleven draws. Maybe not the most pressing issue for Bayesian inference in the era […]
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9:08 PM | No, Michael Jordan didn’t say that!
The names are changed, but the song remains the same. First verse. There’s an article by a journalist, The odds, continually updated, by F.D. Flam in the NY Times to which Andrew responded in blog form, No, I didn’t say that, by Andrew Gelman, on this blog. Second verse. There’s an article by a journalist, […] The post No, Michael Jordan didn’t say that! appeared first on Statistical Modeling, Causal Inference, and Social Science.
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2:43 PM | Free Fibonacci Sequences
John Conway likes playing with the Fibonacci sequence. He invented many new sequences using the following trick. The next number in the sequence is the sum of the two previous number adjusted in some way. Free Fibonacci sequences were invented this way. Here is the recurrence for an n-free Fibonacci sequence: the next number in […]
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1:07 PM | Some questions from our Ph.D. statistics qualifying exam
In the in-class applied statistics qualifying exam, students had 4 hours to do 6 problems. Here were the 3 problems I submitted: In the helicopter activity, pairs of students design paper ”helicopters” and compete to create the copter that takes longest to reach the ground when dropped from a fixed height. The two parameters of the […] The post Some questions from our Ph.D. statistics qualifying exam appeared first on Statistical Modeling, Causal Inference, and Social […]
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12:42 PM | A Case for Anonymous Open Review
I recently reviewed a manuscript for the pioneering journal PeerJ. This presented me with a quandary. PeerJ’s experiment in open reviewing is nicely outlined in their recent post, and includes two steps: reviewers can sign their reports, and authors can publish the review history alongside their accepted paper. My quandary was this: I love the second idea, and think it is an important step forward in opening up the peer review process; but I don’t like to sign my reviews.... Read […]
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10:45 AM | Links (with annotation)
I’ve been heads down writing this week but I wanted to share a bunch of great stuff coming out. Here’s a great interview with machine learning expert Michael Jordan on various things including the big data bubble (hat tip Alan Fekete). I had a similar opinion over a year ago on that topic. Update: here’s […]
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7:02 AM | 'Mitoflashes' indicate acidity changes rather than free radical bursts
As we've written about before, mitochondria generate the energy required by our cells through respiration that involves using an "electrochemical gradient" as an energy store (a bit like pumping water up into a reservoir for energy storage to then harness it flowing down the gradient of a hill to turn a turbine), and produces superoxide (free oxygen radicals) as a by-product (a bit like sparks when the pumps are running hot). The fundamental importance of this machinery which not only delivers […]
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6:14 AM | BibTool on the air
Yesterday night, I realised I had about 30 versions of my “mother of all .bib” bib file, spread over directories and with broken links with the original mother file… (I mean, I always create bib files in new directories by a hard link, ln ~/mother.bib but they eventually end up with a life of their […]
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1:14 AM | Francis Galton could be kind of a jerk
As here (from Hereditary Genius, p. 21) Every tutor knows how difficult it is to drive abstract conceptions, even of the simplest kind, into the brains of most people—how feeble and hesitating is their mental grasp—how easily their brains are mazed—how incapable they are of precision and soundness of knowledge. It often occurs to persons familiar with […]

October 22, 2014

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7:59 PM | Stan 2.5, now with MATLAB, Julia, and ODEs
As usual, you can find everything on the Stan Home Page. Drop us a line on the stan-users group if you have problems with installs or questions about Stan or coding particular models. New Interfaces We’d like to welcome two new interfaces: MatlabStan by Brian Lau, and  Stan.jl (for Julia) by Rob Goedman. The new […] The post Stan 2.5, now with MATLAB, Julia, and ODEs appeared first on Statistical Modeling, Causal Inference, and Social Science.
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4:27 PM | Stuck at 225
My weight loss progress is progress no more. I am stuck at 225. I have my morning routine. I wake up and jog to the facilities; then I weigh myself. Why do I do this in this order? Because I do not use an alarm-clock. I depend on my own hydro-alarm that wakes me up […]
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2:29 PM | Where Do Probability Measures Come From?
Tom Avery explains a categorical construction of the concept of probability measure.
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2:29 PM | Martin Gardner
Come ha ricordato Maurizio Codogno è stato il centenario di Martin Gardner. Recupero oggi con la traduzione di un articolo di David Singmaster uscito su "Nature" nel 2010 come ricordo per la figura di riferimento che ha rappresentato per moltissimi lettori, amanti della matematica e matematici professionisti.Dalla metà degli anni '50 fino ai primi anni '80 del XX sexolo, probabilmente la più nota sezione di Scientific American è stata Mathematical games di Martin […]

Singmaster D. (2010). Obituary: Martin Gardner (1914–2010), Nature, 465 (7300) 884-884. DOI: http://dx.doi.org/10.1038/465884a

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2:29 PM | Controversial App
Just a couple of minutes ago I was watching this video: This video presents an application (PhotoMath) that acts as a smart camera calculator or problem solver. It reads and solves mathematical expressions by using the camera of your mobile device … Continue reading →
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1:56 PM | Sailing between the Scylla of hyping of sexy research and the Charybdis of reflexive skepticism
Recently I had a disagreement with Larry Bartels which I think is worth sharing with you. Larry and I took opposite positions on the hot topic of science criticism. To put things in a positive way, Larry was writing about some interesting recent research which I then constructively criticized. To be more negative, Larry was […] The post Sailing between the Scylla of hyping of sexy research and the Charybdis of reflexive skepticism appeared first on Statistical Modeling, Causal Inference, […]
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8:47 AM | Integration trick
Here’s a clever example from Paul Nahin’s new book Inside Interesting Integrals. Suppose you want to evaluate Since the range of integration is symmetric around zero, you might think to see whether the integrand is an odd function, in which case the integral would be zero. (More on such symmetry tricks here.) Unfortunately, the integrand […]
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