Articles by Chuck Powell

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

May 13, 2019 | 0 Comments

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 | 0 Comments

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 | 0 Comments

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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CHAID v ranger v xgboost – a comparison – July 27, 2018

July 26, 2018 | 0 Comments

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 ... [Read more...]

Creating Slopegraphs with R

June 22, 2018 | 0 Comments

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 | 0 Comments

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...]

CHAID and R – When you need explanation – May 15, 2018

May 14, 2018 | 0 Comments

A modern data scientist using R has access to an almost bewildering number of tools, libraries and algorithms to analyze the data. In my next two posts I’m going to focus on an in depth visit with CHAID (Chi-square automatic interaction detection). The title should give you a hint ... [Read more...]

Announcing CGPfunctions 0.3 – April 20, 2018

April 19, 2018 | 0 Comments

As I continue to learn and grow in using R I have been trying to develop the habit of being more formal in documenting and maintaining the various functions and pieces of code I write. It’s not that I think they are major inventions but they are useful and ... [Read more...]

Writing better R functions part four – April 17, 2018

April 16, 2018 | 0 Comments

In my last four posts I have been working at automating a process, that I am likely to repeat many times, by turning it into a proper R function. In my last post I overcame some real performance problems, combined two sub-functions into one and generally had a workable piece ... [Read more...]

Writing better R functions part three – April 13, 2018

April 12, 2018 | 0 Comments

In my last post I worked on two functions that took pairs of variables from a dataset and produced some nice useful ggplot plots from them. We started with the simplest case, plotting counts of how two variables cross-tabulate. Then we worked our way up to being able to automate ... [Read more...]

Writing better R functions part two – April 10, 2018

April 9, 2018 | 0 Comments

In my last post I started to build two functions that took pairs of variables from a dataset and produced some nice useful ggplot plots from them. We started with the simplest case, plotting counts of how two variables cross-tabulate. Then we worked our way up to being able to ... [Read more...]

Writing better R functions part one – April 6, 2018

April 5, 2018 | 0 Comments

One of the nicest things about working with R is that with very little effort you can customize and automate activities to produce the output you want – just the way you want it. You can contrast that with more monolithic packages that may allow you to do a bit of ... [Read more...]

Fun with M&M’s – April 3, 2018

April 2, 2018 | 0 Comments

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...]

Writing functions for dplyr and ggplot2 – April 2, 2018

April 1, 2018 | 0 Comments

In my last two posts I have been writing about the task of using R to “drive” MS Excel. The first post focused on just the basic mechanics of getting my colleague what she needed. The second post picked up with some ugly inefficient code and made it better using ... [Read more...]

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

March 27, 2018 | 0 Comments

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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Using functions to be more efficient – March 28, 2018

March 27, 2018 | 0 Comments

In yesterday’s post I focused on the task of using R to “drive” MS Excel. I deliberately ended the post with a fully functioning (pun intended) but very ugly set of code. Why “ugly”? Well, because the last set of code wound up repeating 4 lines of code 12 times!
[Read more...]

Introducing the CGPfunctions package

March 21, 2018 | 0 Comments

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...
[Read more...]

Introducing the CGPfunctions package – March 22, 2018

March 21, 2018 | 0 Comments

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 trying... [Read more...]
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