Posts Tagged ‘ binomial ’

MAT8886 exchangeability, credit risk and risk measures

February 10, 2012
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MAT8886 exchangeability, credit risk and risk measures

Exchangeability is an extremely concept, since (most of the time) analytical expressions can be derived. But it can also be used to observe some unexpected behaviors, that we will discuss later on with a more general setting. For instance, in a old...

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Will I ever be a bayesian statistician ? (part 1)

January 20, 2011
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Will I ever be a bayesian statistician ? (part 1)

Last week, during the workshop on Statistical Methods for Meteorology and Climate Change (here), I discovered how powerful bayesian techniques could be, and that there were more and more bayesian statisticians. So, if I was to fully understand app...

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R Commander – logistic regression

June 23, 2010
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R Commander – logistic regression

We can use the R Commander GUI to fit logistic regression models with one or more explanatory variables. There are also facilities to plot data and consider model diagnostics. The same series of menus as for linear models are used to fit a logistic regression model. Fast Tube by Casper The “Statistics” menu provides access to various

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Measuring the length of time to run a function

March 16, 2010
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When writing R code it is useful to be able to assess the amount of time that a particular function takes to run. We might be interested in measuring the increase in time required by our function as the size of the data increases. To illustrate using the system.time function to calculate the time taken to

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Confidence we seek…

November 18, 2009
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Confidence we seek…

Estimating a proportion at first looks elementary. Hail to aymptotics, right? Well, initially it might seem efficient to iuse the fact that . In other words the classical confidence interval relies on the inversion of Wald’s test. A function to ease the computation is the following (not really needed!). waldci<- function(x,n,level){ phat<-sum(x)/n results<-phat + c(-1,1)*qnorm(1-level/2)*sqrt(phat*(1-phat)/n) print(results) } An exact confidence interval is

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