964 search results for "Latex"

Sudokus more random than random!

April 18, 2010
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Sudokus more random than random!

Darren Wraith pointed out this column about sudokus to me. It analyses the paper by Newton and De Salvo published in the Proceedings of the Royal Academy of Sciences A that I cannot access from home. The discussion contains this absurd sentence “Sudoku matrices are actually more random than randomly-generated matrices” which shows how mistreated

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Anecdotal Evidence that Facebook Stores all Clicks?

April 11, 2010
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Anecdotal Evidence that Facebook Stores all Clicks?

This is not really news. A few months ago, news broke that Facebook recorded each user’s clicks and profile views in a database. Of course, I am not at all surprised. I would be more surprised if they didn’t store every single click. By now, most people have some sense as to how Facebook’s recommendation system works. It typically performs...

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An obscure integral

April 7, 2010
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An obscure integral

Here is an email from Thomas I received yesterday about a computation in our book Introducing Monte Carlo Methods with R: I’m currently reading your book “Introduction to Monte Carlo Methods with R” and I quite highly appreciate your work. I’m not able to see how the integral on page 74, that describes the marginal

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Le Monde rank test (corr’d)

April 6, 2010
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Le Monde rank test (corr’d)

Since my first representation of the rank statistic as paired was incorrect, here is the histogram produced by the simulation perm=sample(1:20) saple=sum(abs(sort(perm)-sort(perm))) when . It is obviously much closer to zero than previously. An interesting change is that the regression of the log-mean on produces > lm(log(memean)~log(enn)) Call: lm(formula = log(memean) ~ log(enn)) Coefficients: (Intercept)    

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R Tools for Dynamical Systems ~ R pplane to draw phase planes

April 5, 2010
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R Tools for Dynamical Systems ~ R pplane to draw phase planes

MATLAB has a nice program called pplane that draws phase planes of differential equations models. pplane on MATLAB is an elaborate program with an interactive GUI where you can just type the model to draw the phase planes. The rest you fidget by clicking (to grab the initial conditions) and it draws the dynamics automatically.

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Le Monde rank test (cont’d)

April 5, 2010
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Le Monde rank test (cont’d)

Following a comment from efrique pointing out that this statistic is called Spearman footrule, I want to clarify the notation in namely (a) that the ranks of and are considered for the whole sample, i.e. instead of being computed separately for the ‘s and the ‘s, and then (b) that the ranks are reordered for

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Le Monde rank test

April 4, 2010
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Le Monde rank test

In the puzzle found in Le Monde of this weekend, the mathematical object behind the silly story is defined as a pseudo-Spearman rank correlation test statistic, where the difference between the ranks of the paired random variables and is in absolute value instead of being squared as in the Spearman rank test statistic. I don’t

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CLT Standard Normal Generator

April 2, 2010
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CLT Standard Normal Generator

I’ve found this standard normal random number generator in a number of places, one of which being from one of Paul Wilmott’s books. The idea is that we can use the Central Limit Theorem (CLT) to easily generate values distributed according to a standard normal distribution by using the sum of 12 uniform random

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Opening Statements on Markov Chain Monte Carlo

April 1, 2010
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Opening Statements on Markov Chain Monte Carlo

This quarter I am TAing UCLA’s Statistics 102C. Introduction to Monte Carlo Methods for Professor Qing Zhou. This course did not exist when I was an undergraduate, and I think it is pretty rare to teach Monte Carlo (minus the bootstrap if you count that) or MCMC to undergrads. I am excited about this class because to me, MCMC...

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Because it’s Thursday: Epidemiology of the Undead

April 1, 2010
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Because it’s Thursday: Epidemiology of the Undead

Noted statistician Andrew Gelman has teamed up with occultist George Romero to address the most serious public-health threat of out time: Zombies. They've published a paper in the journal Biomastika, "How many zombies do you know?" to propose the use of indirect survey methods to measure outbreaks of the undead: Abstract: The zombie menace has so far been studied...

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