Monthly Archives: February 2013

Unknown Variance Two-Tailed Test of Population Mean

February 11, 2013
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Unknown Variance Two-Tailed Test of Population Mean

Question The mean safety audit score of ACME Co. stores in New York (n=200) was 74.3pts February last year.  Suppose we decided to sample 22 out of the 200 stores one year later. We find that the sample mean is 78.6pts and the sample standard deviation is 3.2pts.  Can we reject the null hypothesis that

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One R Function A Day.

February 11, 2013
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As a R user with 5 years experience, I still have some basic functions that never used or never thought they could exist. Many times I was suprised with some elegant R functions, such like strwidth, parent.frame, etc. No one can know all R functions (...

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Variability of predicted portfolio volatility

February 11, 2013
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Variability of predicted portfolio volatility

A prediction of a portfolio’s volatility is an estimate — how variable is that estimate? Data The universe is 453 large cap US stocks. The variance matrices are estimated with the daily returns in 2012. Variance estimation was done with Ledoit-Wolf shrinkage (shrinking towards equal correlation). Two sets of random portfolios were created.  In both … Continue reading...

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“Introduction to R” Course Milano; February 21-22, 2013

February 11, 2013
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Milano R net, in collaboration with Quantide, organizes "Introduction to R" Course February 21-22, 2013 Course description This two days course aims to provide an overview of the basic R environment and its applications. This course is intendended as a … Continue reading →

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analyze health professional shortage areas (hpsa) with r

February 11, 2013
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a health professional shortage area (hpsa) is a geographic area, population group, or health care facility that has been designated by the united states government as having an insufficient supply of medical providers, based on certain provider-to-popu...

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Using R: accessing PANTHER classifications

February 10, 2013
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Using R: accessing PANTHER classifications

Importing, subsetting, merging and exporting various text files with annotation (in the wide sense, i.e. anything that might help when interpreting your experiment) is not computation and it’s not biology either, but it’s housekeeping that needs to be done. Everyone has a weapon of choice for general-purpose scripting and mine is R. Yes, this is

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Finding Patterns Amongst Binary Variables with the homals Package

February 10, 2013
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Finding Patterns Amongst Binary Variables with the homals Package

It’s survey analysis season for me at work!  When analyzing survey data, the one kind of analysis I have realized that I’m not used to doing is finding patterns in binary data.  In other words, if I have a question … Continue reading →

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Publishing from R+knitr to WordPress

February 10, 2013
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Publishing from R+knitr to WordPress

Tal Galili asked a question on StackOverflow on publishing blog posts to WordPress from R + knitr. William K. Morris has written a solution long time ago, and I tweaked it a little bit and created a function knit2wp() in the development version of knit...

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Using deSolve package

February 9, 2013
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(This article was first published on Just Another R Blog, and kindly contributed to R-bloggers) To leave a comment for the author, please follow the link and comment on their blog: Just Another R Blog. R-bloggers.com offers daily e-mail updates about R news and tutorials on topics such as: Data science, Big Data, R jobs, visualization (ggplot2, Boxplots, maps,...

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Exposure with binomial responses

February 9, 2013
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Exposure with binomial responses

Last week, we’ve seen how to take into account the exposure to compute nonparametric estimators of several quantities (empirical means, and empirical variances) incorporating exposure. Let us see what can be done if we want to model a binomial response. The model here is the following: , the number of claims  on the period  is unobserved the number of...

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