As reported on the Kaggle blog No Free Hunch, R remains the preferred tool for data scientists seeking to win the prizes in the predictive modeling competitions:
More than 30% of Kaggle competitors report using R for their analysis, up from 22% a year ago. R's flexibility and the breadth of packages for machine learning and predictive modeling make it a natural choice for Kaggle's competitors, where as little as a 0.01% improvement in prediction accuracy can mean the difference between taking the top prize and missing out. In fact, Kaggle reports that more than 50% of compeition winners used R in their analysis.
You can read more about how Kaggle competitors use R to build powerful predictive models in the white paper, "R Competition Brings Out the Best in Data Analytics". And if you're competing in a Kaggle competition you can download Revolution R Enteprise for free, and make use of its improved performance and big-data analytics for R to build competitive predictive models.
No Free Hunch: Kagglers’ Favorite Tools
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Zero Inflated Models and Generalized Linear Mixed Models with R.
Zuur, Saveliev, Ieno (2012).