# Posts

### October 26, 2014

+

7:46 PM | Evariste Galois

As you have observed I omitted Evariste Galois born on 25th October 1811 from my daily posts and this is because he is the one that influenced me to start the event ‘Celebrate Mathematicians in October‘ and so I decided … Continue reading →

+

5:06 PM | Il (non) carnevale della fisica #2

Il premio Nobel venne assegnato per la prima volta nel 1901 a seguito delle ultime disposizioni testamentarie di Alfred Nobel, chimico e filantropo nonché inventore della dinamite.Il premio è diventato ben presto uno dei più prestigiosi al mondo e, nell'ambito della fisica, il primo a riceverlo fu lo scopritore dei raggi X, il tedesco Wilhelm Conrad Röntgenin riconoscimento dello straordinario servizio reso per la scoperta delle importanti radiazioni che in seguito
[…]

+

2:31 PM | Regge theory

http://t.co/alaasqcHwl @ulaulaman says #goodbye to #TullioRegge In quantum physics, Regge theory is the study of the analytic properties of scattering as a function of angular momentum, where the angular momentum is not restricted to be an integer but is allowed to take any complex value. The nonrelativistic theory was developed by Tullio Regge in 1957.Following Chew and Frautschi (pdf), the key papers by Tullio Regge are: Regge T. (1959). Introduction to complex orbital momenta, Il Nuovo
[…]

+

See this recent post for background. Here’s the question: You are designing an experiment where you are estimating a linear dose-response pattern with a dose that x can take on the values 1, 2, 3, and the response is continuous. Suppose that there is no systematic error and that the measurement variance is proportional to x. You […]
The post Solution to the sample-allocation problem appeared first on Statistical Modeling, Causal Inference, and Social Science.

+

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

Citation

### October 25, 2014

+

10:14 PM | marauders of the lost sciences

The editors of a new blog entitled Marauders of the Lost Sciences (Learn from the giants) sent me an email to signal the start of this blog with a short excerpt from a giant in maths or stats posted every day: There is a new blog I wanted to tell you about which excerpts one […]

+

8:47 PM | When to buy airplane tickets

From Yahoo Travel: what day of the week to buy airplane tickets for the best deal. Short version: round trip domestic airfares average about $430 on weekends and about $500 on weekdays, so buy on the weekend. The Yahoo piece is, in turn, a condensation of this piece from the Wall Street Journal. The WSJ […]

+

The prime number theorem can be expressed as the assertion as , where is the von Mangoldt function. It is a basic result in analytic number theory, but requires a bit of effort to prove. One “elementary” proof of this theorem proceeds through the Selberg symmetry formula where the second von Mangoldt function is defined […]

+

“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., […]

+

See this recent post for background. Here’s the question: It is sometimes said that the p-value is uniformly distributed if the null hypothesis is true. Give two different reasons why this statement is not in general true. The problem is with real examples, not just toy examples, so your reasons should not involve degenerate situations such as […]
The post Solution to the problem on the distribution of p-values appeared first on Statistical Modeling, Causal Inference, and
[…]

+

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 […]

+

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

+

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 […]

+

What parking spot number is the car parked in? Share:

+

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 […]

+

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
[…]

+

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
[…]

+

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 →

+

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.

+

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? […]

+

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
[…]

+

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

+

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 […]

+

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.

+

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 […]

+

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
[…]

+

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
[…]

+

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 […]

+

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
[…]

+

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 […]