Blog Archives

It is "simply" the average value

January 24, 2012
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It is "simply" the average value

for some obscure reasons, simple things are usually supposed to be simple. Recently, on the internet, I saw a lot of posts on the "average time in which you hold a stock", and two rather different values are mentioned "Take any stock in the United ...

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Even odds

January 22, 2012
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Even odds

This evening, I found a nice probabilistic puzzle on http://www.futilitycloset.com/ "A bag contains 16 billiard balls, some white and some black. You draw two balls at the same time. It is equally likely that the two will be the same color as diff...

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MAT8886 Extremes and sums (of i.i.d. random variables)

January 20, 2012
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MAT8886 Extremes and sums (of i.i.d. random variables)

Yesterday, we have discussed briefly sums and maximas of i.i.d. random variables using the concept of subexponential distributions. Today, we will introduce the concept of regular variation: a positive function is said to be regularly varying (at i...

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Gold price and fear

January 18, 2012
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Gold price and fear

Via @theEconomist, I understood that there might be connections between the price of Gold (which is said to be extremely high nowadays) and the VIX SP500 index (the option volatility index, i.e. the so-called "fear index", as discussed - in French-...

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Infidelity and econometrics

January 17, 2012
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Infidelity and econometrics

On http://www.bakadesuyo.com, there was recently an interesting discussion about infidelity, the key question being "at what ages are men and women most likely to have affairs?" The discussion is based on some graphs, e.g.The source is a paper b...

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MAT8886 Fisher-Tippett theorem and limiting distribution for the maximum

January 12, 2012
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MAT8886 Fisher-Tippett theorem and limiting distribution for the maximum

Tomorrow, we will discuss Fisher-Tippett theorem. The idea is that there are only three possible limiting distributions for normalized versions of the maxima of i.i.d. samples . For bounded distribution, consider e.g. the uniform distribution on t...

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Quel lancer de dé faire à Serpents et Échelles ?

December 21, 2011
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Quel lancer de dé faire à Serpents et Échelles ?

Hier soir, j’évoquais l’utilisation des chaînes de Markov au jeu Serpents et Échelles. Comme me le faisait remarquer Jean-Philippe, de manière assez étrange, les enfants sont toujours beaucoup plus content après avoir fait un 6 qu’après avoir fait un 1. Mais est-ce réellement la valeur optimale que le dé doit prendre ? Ça dépend bien sûr de la position....

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Maps with R, and polygon boundaries

December 21, 2011
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Maps with R, and polygon boundaries

With R, it is extremely easy to draw maps. Let us start with something simple, like French regions. Baptiste mentioned on his blog that shapefiles can be downloaded from http://ign.fr/ website. Hence, if you extract the zip file, it is possible to ...

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Basics on Markov Chain (for parents)

December 20, 2011
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Basics on Markov Chain (for parents)

Markov chains is a very interesting and powerful tool. Especially for parents. Because if you think about it quickly, most of the games our kids are playing at are Markovian. For instance, snakes and ladders… It is extremely easy to write down the transition matrix, one just need to define all snakes and ladders. For the one above, we...

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Basics on Markov Chain (for parents)

December 20, 2011
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Basics on Markov Chain (for parents)

Markov chains is a very interesting and powerful tool. Especially for parents. Because if you think about it quickly, most of the games our kids are playing at are Markovian. For instance, snakes and ladders... It is extremely easy to write down th...

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