# Posts Tagged ‘ R-english ’

## Kendall’s function for copulas

September 12, 2012
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As mentioned in the course on copulas, a nice tool to describe dependence it Kendall's cumulative function. Given a random pair with distribution  , define random variable . Then Kendall's cumulative function is Genest and Rivest (1993) intr...

## Association and concordance measures

September 12, 2012
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Following the course, in order to define assocation measures (from Kruskal (1958)) or concordance measures (from Scarsini (1984)), define a concordance function as follows: let be a random pair with copula , and with copula . Then define the so-...

## Unit root, or not ? is it a big deal ?

September 10, 2012
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Consider a time series, generated using set.seed(1) E=rnorm(240) X=rep(NA,240) rho=0.8 X=0 for(t in 2:240){X=rho*X+E} The idea is to assume that an autoregressive model can be considered, but we don't know the value of the parameter. ...

## That damn R-squared !

September 7, 2012
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Another post about the R-squared coefficient, and about why, after some years teaching econometrics, I still hate when students ask questions about it. Usually, it starts with "I have a _____ R-squared... isn't it too low ?" Please, feel free to fi...

## Inference and autoregressive processes

September 6, 2012
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Consider a (stationary) autoregressive process, say of order 2, for some white noise with variance . Here is a code to generate such a process, > phi1=.5 > phi2=-.4 > sigma=1.5 > set.seed(1) > n=240 > WN=rnorm(n,sd=sigma) > ...

## Border bias and weighted kernels

August 31, 2012
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With Ewen (aka @3wen), not only we have been playing on Twitter this month, we have also been working on kernel estimation for densities of spatial processes. Actually, it is only a part of what he was working on, but that part on kernel estimation...

## Visualizing uncertainty using Jackknife

July 1, 2012
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Once again, I (re)discovered last week at the Rmetrics conference that old toolds can be extremely interesting to illustrate complex ideas, like uncertainty in fnancial markets, and stock prices. For instance a 99.5% quantile: we look for the scena...

## Simple and heuristic optimization

June 29, 2012
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This week, at the Rmetrics conference, there has been an interesting discussion about heuristic optimization. The starting point was simple: in complex optimization problems (here we mean with a lot of local maxima, for instance), we do not ne...

## Actuarial models with R, Meielisalp

June 23, 2012
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I will be giving a short course in Switzerland next week, at the 6th R/Rmetrics Meielisalp Workshop & Summer School on Computational Finance and Financial Engineering organized by ETH Zürich, https://www.rmetrics.org/. The long...

## Pricing options on multiple assets (part 1) with trees

June 19, 2012
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I am a big fan of trees. It is a very nice way to see how financial pricing works, for derivatives. An with a matrix-based language (R for instance), it is extremely simple to compute almost everything. Even multiple assets options. Let us see how ...