1290 search results for "latex"

predictNLS (Part 2, Taylor approximation): confidence intervals for ‘nls’ models

August 26, 2013
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$predictNLS (Part 2, Taylor approximation): confidence intervals for ‘nls’ models$

Initial Remark: Reload this page if formulas don’t display well! As promised, here is the second part on how to obtain confidence intervals for fitted values obtained from nonlinear regression via nls or nlsLM (package ‘minpack.lm’). I covered a Monte Carlo approach in http://rmazing.wordpress.com/2013/08/14/predictnls-part-1-monte-carlo-simulation-confidence-intervals-for-nls-models/, but here we will take a different approach: First- and second-order

From SVG to probability distributions [with R package]

August 25, 2013
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$From SVG to probability distributions [with R package]$

Hey, To illustrate generally complex probability density functions on continuous spaces, researchers always use the same examples, for instance mixtures of Gaussian distributions or a banana shaped distribution defined on with density function: If we draw a sample from this distribution using MCMC we obtain a plot like this one: Clearly it doesn’t really look

Electronic lab notebook

August 20, 2013
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I was interested to read C. Titus Brown‘s recent post, “Is version control an electronic lab notebook?” I think version control is really important, and I think all computational scientists should have something equivalent to a lab notebook. But I think of version control as serving needs orthogonal to those served by a lab notebook.

Weak Learners

August 20, 2013
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Tonight's session of R bore just enough fruit that I finally am writing my sophomore entry. I was browsing the slides from a machine learning lecture given by Leo Breiman and came across a relatively simple example he used to introduce the notions...

Endogenous Spatial Lags for the Linear Regression Model

August 18, 2013
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Over the past number of years, I have noted that spatial econometric methods have been gaining popularity. This is a welcome trend in my opinion, as the spatial structure of data is something that should be explicitly included in the empirical modelling procedure. Omitting spatial effects assumes that the location co-ordinates for observations are unrelated

August 15, 2013
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A new minor release 3.910.0 of Armadillo came out a few days ago. A new RcppArmadillo release 0.3.910.0 was provided rightaway, and after a brief back-and-forth with CRAN (mostly having to do with the non-standard vignette corresponding to our CSD...

Creating a Quick Report with knitr, xtable, R Markdown, Pandoc (and some OpenBLAS Benchmark Results)

August 15, 2013
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To cut a long story short, I always wanted to write professional-looking documents (technical reports and potentially my thesis) with R codes. No more copy and paste. No more Microsoft Word. At the same time, I don't feel comfortable with LaTeX. Somehow I found a workaround with knitr, xtable, R Markdown...

Census Atlas Japan

August 15, 2013
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The 2011 Census Open Atlas project has been put on hold recently as various other research projects have intervened – more on these soon. However, over the summer  Chris Brunsdon and I have taken a research trip to Ritsumeikan University (Japan) where we visited Keiji Yano and Tomoki Nakaya. As part of this trip I began developing a census atlas for

predictNLS (Part 1, Monte Carlo simulation): confidence intervals for ‘nls’ models

August 14, 2013
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$predictNLS (Part 1, Monte Carlo simulation): confidence intervals for ‘nls’ models$

Those that do a lot of nonlinear fitting with the nls function may have noticed that predict.nls does not have a way to calculate a confidence interval for the fitted value. Using confint you can obtain the error of the fit parameters, but how about the error in fitted values? ?predict.nls says: “At present se.fit

Exposure as a possible explanatory variable

August 13, 2013
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$Y_i$

Iin insurance pricing, the exposure is usually used as an offset variable to model claims frequency. As explained many times on this blog (e.g. here), and in my notes, if we have to identical drivers, but one with an exposure of 6 months, and the other one of one year, it should be natural to assume that, on average,...