applied statistics

Text Mining

October 15, 2012 | Wesley

When it comes down to it R does a really good job handling structured data like matrices and data frames. However, its ability to work with unstructured data is still a work in progress. It can and it does handle text mining but the documentation is incomplete and the capabilities ... [Read more...]

Association Rule Learning and the Apriori Algorithm

September 26, 2012 | Wesley

Association Rule Learning (also called Association Rule Mining) is a common technique used to find associations between many variables. It is often used by grocery stores, retailers, and anyone with a large transactional databases. It’s the same way that Target knows your pregnant or when you’re buying an ... [Read more...]

Data Frames and Transactions

September 24, 2012 | Wesley

Transactions are a very useful tool when dealing with data mining.  It provides a way to mine itemsets or rules on datasets. In R the data must be in transactions form.  If the data is only available in a data.frame then to create (or coerce) the data frame to ... [Read more...]

Power Analysis and the Probability of Errors

September 22, 2012 | Wesley

Power analysis is a very useful tool to estimate the statistical power from a study. It effectively allows a researcher to determine the needed sample size in order to obtained the required statistical power. Clients often ask (and rightfully so) what the sample size should be for a proposed project. ... [Read more...]


September 15, 2012 | Wesley

N-Way ANOVA example Two-way analysis of variance is where the rubber hits the road, so to speak. This extends the concepts of ANOVA with only one factor to two factors. When there are two factors this means that there can be an interaction between the two factors that should be ... [Read more...]


September 11, 2012 | Wesley

One-Way ANOVA Analysis of variance is a tool used for a variety of purposes. Applications range from a common one-way ANOVA, to experimental blocking, to more complex nested designs. This first ANOVA example provides the necessary tools to analyze data using this technique. This example will show a basic one-way ... [Read more...]

Kendall’s Tau

September 5, 2012 | Wesley

Kendall’s Tau This is an example of Kendall’s Tau rank correlation.  This is similar to Spearman’s Rho in that it is a non-parametric measure of correlation on ranks.  It is an appropriate measure for ordinal data and is fairly straight forward when there are no ties in ... [Read more...]

Spearman’s Rho

August 30, 2012 | Wesley

Spearman’s Rho Rank Correlation There are generally three types of correlation that a researcher may encounter: Pearson’s r, Kendall’s Tau, and Spearman’s Rho.  They each have their own uses and applications depending on the da... [Read more...]

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