335 search results for "evaluation"

Entering the field as a data scientist with certification

August 22, 2014
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By Neera Talbert, VP Services and Ben Wiley, R Programmer at Revolution Analytics By now, everyone should be familiar with the data scientist boom. Simply logging onto LinkedIn reveals a seemingly infinite number of people with words and phrases like “Data Scientist”, “Big Data Specialist”, and “Analytics” in their title. A few weeks ago, an article floated around the...

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Optimizing with R expressions

August 21, 2014
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Optimizing with R expressions

I recently discovered a powerful use for R expression()’sSay you are trying to fit some experimental data to the following nonlinear equation: Ky0eu(x−tl)K+y0(eu∗(x−tl)−1)+b1+(b0−b1)e−kx+b2x with the independent variable x using nlminb() as the minimization optimizer.This sort of work is significantly improved (i.e. faster with better convergence) if an analytical gradient vector and a Hessian matrix for the objective function are provided....

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Simulating species abundance data with coenocliner

July 31, 2014
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Simulating species abundance data with coenocliner

Coenoclines are, according to the Oxford Dictionary of Ecology (Allaby 1998), “gradients of communities (e.g. in a transect from the summit to the base of a hill), reflecting the changing importance, frequency, or other appropriate measure of different species populations”. In much ecological research, and that of related fields, data on these coenoclines are collected and analyzed in a variety...

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Announcing Shiny Server Pro 1.2

July 24, 2014
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Announcing Shiny Server Pro 1.2

RStudio is very pleased to announce the general availability of Shiny Server Pro 1.2. Download a free 45 day evaluation of Shiny Server Pro 1.2 Shiny Server Pro 1.2 adds support for R Markdown Interactive Documents in addition to Shiny applications. Learn more about Interactive Documents by registering for the Reproducible Reporting webinar August 13

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Bayesian Naive Bayes for Classification with the Dirichlet Distribution

July 14, 2014
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I have a classification task and was reading up on various approaches. In the specific case where all inputs are categorical, one can use “Bayesian Naïve Bayes” using the Dirichlet distribution.  Poking through the freely available text by Barber, I found a rather detailed discussion in chapters 9 and 10, as well as example matlab code for the...

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Le Monde puzzle [#875]

July 11, 2014
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Le Monde puzzle [#875]

I learned something in R today thanks to Le Monde mathematical puzzle: A two-player game consists in A picking a number n between 1 and 10 and B and A successively choosing and applying one of three transforms to the current value of n n=n+1, n=3n, n=4n, starting with B, until n is larger than

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Are Consumer Preferences Deep or Shallow?

July 8, 2014
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Are Consumer Preferences Deep or Shallow?

John Hauser, because no one questions his expertise, is an excellent spokesperson for the viewpoint that consumer preferences are real, as presented in his article "Self-Reflection and Articulated Consumer Preferences." Simply stated, preferences are e...

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analyze the demographic and health surveys (dhs) with r

July 8, 2014
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professors of public health 101 probably cite the results of the demographic and health surveys (dhs) more than all other data sources combined.  funded by the united states agency for international development (usaid) and administered by the tech...

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DSC 2014. Day 1

July 7, 2014
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DSC 2014. Day 1

This is a report of the first day of the Directions in Statistical Computing (DSC) conference that took place in Brixen, Italy (See here for an introduction). Performance enhancements were the main theme of the day, covering not just improvements … Continue reading →

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Automatic bias correction doesn’t fix omitted variable bias

July 4, 2014
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Automatic bias correction doesn’t fix omitted variable bias

Page 94 of Gelman, Carlin, Stern, Dunson, Vehtari, Rubin “Bayesian Data Analysis” 3rd Edition (which we will call BDA3) provides a great example of what happens when common broad frequentist bias criticisms are over-applied to predictions from ordinary linear regression: the predictions appear to fall apart. BDA3 goes on to exhibit what might be considered Related posts:

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