1557 search results for "regression"

Generation of E-Learning Exams in R for Moodle, OLAT, etc.

December 20, 2012
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Generation of E-Learning Exams in R for Moodle, OLAT, etc.

(Guest post by Achim Zeileis) Development of the R package exams for automatic generation of (statistical) exams in R started in 2006 and version 1 was published in JSS by Gr?n and Zeileis (2009). It was based on standalone Sweave exercises, that can be combined …Read more »

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Italian elections (1)

December 19, 2012
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Italian elections (1)

You'd think that the last week before the holidays would be very quiet and not much would be going on. Well, if you did, you'd be wrong, I guess, as the last few days have been quite busy (for many reasons). Anyway, I managed to track down some be...

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Making Friends with Multicollinearity

December 18, 2012
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Not every system of independent variables can be decomposed into separate components, each with its own unique contribution.  Sometimes our individual variables behave “as a unit” and thus become so entangled that we cannot say where the effect of one variable begins and the effect of another variable ends.  In such cases, it might be best to ignore the ...

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analyze the behavioral risk factor surveillance system (brfss) with r and monetdb

December 17, 2012
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experimental.  the behavioral risk factor surveillance system (brfss) aggregates behavioral health data from 400,000 adults via telephone every year.  it's um *clears throat* the largest telephone survey in the world and it's gotta lotta uses...

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Fractional Logit Model with Python

December 16, 2012
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Fractional Logit Model with Python

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Matrix Algebra Useful for Statistics

December 16, 2012
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Matrix Algebra Useful for Statistics

I was having a conversation with an acquaintance about courses that were particularly useful in our work. My forestry degree involved completing 50 compulsory + 10 elective† courses; if I had to choose courses that were influential and/or really useful they would be Operations Research, Economic Evaluation of Projects, Ecology, 3 Calculus and 2 Algebras.

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The R journal – Volume 4/2, December 2012

December 16, 2012
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Download complete issue Refereed articles may be downloaded individually using the links below. Table of Contents Editorial 3   Contributed Research Articles What’s in a Name? Paul Murrell 5 It’s Not What You Draw,It’s What You Don’t Draw Paul Murrell 13 Debugging grid Graphics Paul Murrell and Velvet Ly 19 frailtyHL: A Package for Fitting...

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Making Data Visually Appealing

December 16, 2012
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Making Data Visually Appealing

I’ve recently been considering the graphical presentation of data. I get the feeling that we, ecologists/scientsits, could be better at data presentation. Graphs must be informative, but they don’t have to be ugly. I think that making visually appealing charts … Continue reading →

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What is Correctness for Statistical Software?

December 14, 2012
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What is Correctness for Statistical Software?

Introduction A few months ago, Drew Conway and I gave a webcast that tried to teach people about the basic principles behind linear and logistic regression. To illustrate logistic regression, we worked through a series of progressively more complex spam detection problems. The simplest data set we used was the following: This data set has

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Trading with SVMs: Performance

December 13, 2012
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Trading with SVMs: Performance

To get a feeling of SVM performance in trading, I run different setups on the S&P 500 historical data from … the 50s. The main motif behind using this decade was to decide what parameters to vary and what to keep steady prior to running the most important tests. Treat it as an “in-sample” test

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