# Posts Tagged ‘ proportion ’

## Hot Spot Mapping in R: Illustrating Relative Seasonal Risk

October 5, 2011
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In recent months, IDV has taken steps to incorporate the powerful statistical engine, R, as a viable connection to Visual Fusion.  R has a robust and growing set of libraries and a community that is constantly thumping away on improvements.  ...

## Want to say one thing and the exact oppositive with strong confidence ?

March 15, 2011
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No need to do politics. Just take a statistical course. And I do not talk about misinterpretation of statistics, but I talk about the mathematical foundations of statistical tests. Consider the following parametric test, with a one-dimensional para...

## Margin of error, and comparing proportions in the same sample

October 15, 2010
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I recently tried to answer a simple question, asked by @adelaigue. Actually, I thought that the answer would be obvious... but it is a little bit more compexe than what I thought. In a recent pool about elections in Brazil, it was mentionned in a ...

## 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