Articles by Chuck Powell

Upgrading to R 3.6.0 on a Mac – May 14, 2019

May 13, 2019 | Chuck Powell

Every time there is a new major update from The R Foundation (like the recent 3.6.0 release in April). I’m always happy to see the continuing progress and the combination of new features and bug fixes, but I also dread the upgrade because it means I have to address the ... [Read more...]

ANCOVA example – April 18, 2019

April 17, 2019 | Chuck Powell

I recently had the need to run an ANCOVA, not a task I perform all that often and my first time using R to do so (I’ve done it in SPSS and SAS before). Having a decent theoretical idea of what I had to do I set off in ... [Read more...]

CHAID vs. ranger vs. xgboost — a comparison

July 29, 2018 | Chuck Powell

In an earlier post, I focused on an in-depth visit with CHAID (Chi-square automatic interaction detection). Quoting myself, I said “As the name implies it is fundamentally based on the venerable Chi-square test – and while not the most powerful (in terms of detecting the smallest possible differences) or the fastest, ...
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Creating Slopegraphs with R

June 22, 2018 | Chuck Powell

Presenting data results in the most informative and compelling manner is part of the role of the data scientist. It's all well and good to master the arcana of some algorithm, to manipulate and master the numbers and bend them to your will to produce a “solution” that is both ...
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CHAID and caret – a good combo – June 6, 2018

June 5, 2018 | Chuck Powell

In an earlier post I focused on an in depth visit with CHAID (Chi-square automatic interaction detection). There are lots of tools that can help you predict an outcome, or classify, but CHAID is especially good at helping you explain to any audience how the model arrives at it’s ... [Read more...]

Fun with M&M’s – April 3, 2018

April 2, 2018 | Chuck Powell

In this post we’re going to explore the Chi Squared Goodness of Fit test using M&M’s as our subject material. From there we’ll take a look at simultaneous confidence intervals a.k.a. multiple comparisons. On the R side of things we’ll make use of ... [Read more...]

Using R to ‘drive’ MS Excel – 3/27/2018

March 27, 2018 | Chuck Powell

I have until recently made it a habit to draw a clear distinction about using R for data analysis and Microsoft Excel for other office productivity tasks. I know there are people who use Excel to process data and even (gasp) to teach statistics with it. But I’m a ...
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Introducing the CGPfunctions package

March 21, 2018 | Chuck Powell

Overview This package includes functions that I find useful for teaching statistics as well as actually practicing the art. They typically are not “new” methods but rather wrappers around either base R or other packages and concepts I’m tryin...
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