1420 search results for "regression"

Generating all subsets of a set

April 20, 2012
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Generating all subsets of a set

Recently I have calculated Banzhaf power index. I required generation of all subsets of a given set. The code given there was a bit complex and I have decided to write a simple function calculating it. As an example of its application I reproduce Figur...

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Simple tools for building a recommendation engine

April 19, 2012
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By Joseph Rickert Revolution’s resident economist, Saar Golde, is very fond of saying that “90% of what you might from a recommendation engine can be achieved with simple techniques”. To illustrate this point (without doing a lot of work), we downloaded the million row movie dataset from www.grouplens.org with the idea of just taking the first obvious exploratory step:...

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R Quickie: Custom Panel Functions and Default Arguments

April 16, 2012
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Sometimes the basic functionality in lattice graphics isn't enough. Custom "panel functions" are one approach to fully customizing the lattice graphics system. Two examples are given below illustrating how to define an (inline) custom panel function fo...

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Instrumental Variables without Traditional Instruments

April 14, 2012
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Instrumental Variables without Traditional Instruments

Typically, regression models in empirical economic research suffer from at least one form of endogeneity bias. The classic example is economic returns to schooling, where researchers want to know how much increased levels of education affect income. Estimation using a simple linear model, regressing income on schooling, alongside a bunch of control variables, will typically

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PostgreSQL Scalability Analysis Deconstructed

April 11, 2012
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PostgreSQL Scalability Analysis Deconstructed

In 2010, I presented my universal scalability law (USL) at the SURGE conference. I came away with the impression that nobody really understood what I was talking about (quantifying scalability) or, maybe DevOps types thought it was all too hard (math). Since then, however, I've come to find out that people like Baron Schwartz did get it...

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Getting Started with JAGS, rjags, and Bayesian Modelling

April 10, 2012
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This post provides links to various resources on getting started with Bayesian modelling using JAGS and R. It discusses: (1) what is JAGS; (2) why you might want to perform Bayesian modelling using JAGS; (3) how to install JAGS; (4) where to find furth...

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Using SNA in Predictive Modeling

April 10, 2012
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Using SNA in Predictive Modeling

In a previous post, I described the basics of social network analysis. I plan to extend that example here with an application in predictive analytics. Let's suppose we have the following network (visualized in R)Suppose we have used the igraph package ...

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Correlation Matrix (Constituents)

April 9, 2012
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Correlation Matrix (Constituents)

It is important to understand as better as possible our sample set before to develop the regression. Continuing with the “Y” matrix (constituent’s matrix) we have to observe the correlation matrix.In the R Graph Gallery, we can get the code to dr...

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The lm() function with categorical predictors

April 8, 2012
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The lm() function with categorical predictors

What's with those estimates?By Ben OgorekIn R, categorical variables can be added to a regression using the lm() function without a hint of extra work. But have you ever look at the resulting estimates and wondered exactly what they were?First, let's define a data set.set.seed(12255)n = 30sigma = 2.0AOV.df <- data.frame(category = c(rep("category1", n)     ...

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RNA-Seq Methods & March Twitter Roundup

April 6, 2012
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There were lots of interesting developments this month that didn't work their way into a full blog post. Here is an incomplete list of what I've been tweeting about over the last few weeks. But first I want to draw your attention to the latest manuscri...

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