1488 search results for "Regression"

Why Learn R? It’s the language of Statistics

June 24, 2010
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In the Introduction to his book “R for SAS and SPSS Users” (Springer 2009) Robert Muenchen offers ten reasons for learning R if you already know SAS or SPSS. All ten reasons say something important about R. However, his fourth reason: “R’s language is more powerful than SAS or SPSS. R developers write most of their analytic methods using...

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Linear Modeling in R and the Hubble Bubble

June 22, 2010
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Linear Modeling in R and the Hubble Bubble

Here is a scatter plot with the coordinate labels deliberately omitted. Figure 1. Do you see any trends? How would you model these data? It just so happens that this scatterplot is arguably the most famous scatterplot in history. One aficionado, writing more than forty years after its publication, commented skeptically :" data points were consequently spread...

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Linear Modeling in R and the Hubble Bubble

June 22, 2010
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Linear Modeling in R and the Hubble Bubble

Here is a scatter plot with the coordinate labels deliberately omitted. Figure 1. Do you see any trends? How would you model these data? It just so happens that this scatterplot is arguably the most famous scatterplot in history. One aficionado, writing more than forty years after its publication, commented skeptically :" data points were consequently spread...

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Example 7.42: Testing the proportionality assumption

June 21, 2010
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Example 7.42: Testing the proportionality assumption

In addition to the non-parametric tools discussed in recent entries, it's common to use proportional hazards regression, (section 4.3.1) also called Cox regression, in evaluating survival data.It's important in such models to test the proportionality a...

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Do Not Log-Transform Count Data, Bitches!

June 17, 2010
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Do Not Log-Transform Count Data, Bitches!

OK, so, the title of this article is actually Do not log-transform count data, but, as @ascidacea mentioned, you just can’t resist adding the “bitches” to the end. Onwards. If you’re like me, when you learned experimental stats, you were taught to worship at the throne of the Normal Distribution. Always check your data and

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Learning R

June 17, 2010
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When R is brought up as a possibility for doing statistics or data mining or any sort of predictive analytics among non R users, someone will invariably point out that R has a “steep learning curve”, and the response among those gathered usually includes a significant amount of head nodding. Even those who have put in heroic efforts to...

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Statistical Analysis and Visualization of the Drug War in Mexico

June 15, 2010
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Statistical Analysis and Visualization of the Drug War in Mexico

On December 11, 2006 Felipe Calderon, as the first significant act of his presidency, sent the army to his home state of Michoacan. He claimed that it was to regain control of territories lost to the drug cartels, and indeed, a new cartel had started operating in Michocan. But the fact that he won the election by the slim margin of...

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Statistical Analysis and Visualization of the Drug War in Mexico

June 15, 2010
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Statistical Analysis and Visualization of the Drug War in Mexico

On December 11, 2006 Felipe Calderon, as the first significant act of his presidency, sent the army to his home state of Michoacan. He claimed that it was to regain control of territories lost to the drug cartels, and indeed, a new cartel had started operating in Michocan. But the fact that he won the election by the slim margin of...

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Dynamic Modeling 3: When the first-order difference model doesn’t cut it

June 12, 2010
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Dynamic Modeling 3: When the first-order difference model doesn’t cut it

Data must be selected carefully.  The predictive usefulness of the model is grossly diminished if outliers taint the available data.  Figure 1, for instance, shows the Defense spending (as a fraction of the national budget) between 1948 and 1968. Note how the trend curve (as defined by our linear difference model from the last post: see

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Performance benefits of linking R to multithreaded math libraries

June 11, 2010
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R wasn't originally designed as a multithreaded application -- multiprocessor systems were still rare when the R Project was first conceived in the mid-90's -- and so, by default, R will only use one processor of your dual-core laptop or quad-core desktop machine when doing calculations. For calculations that take a long time, like big simulations or modeling of...

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