Publications by Wesley
Free e-Copy of Bayesian Computation with R (Use R)
Editors note: It looks like Amazon has completely removed the Kindle version of the book from their web site. I still see the e-book for sale using the Kindle app directly but you’ll have to pay the regular price. ==================== Amazon is currently making the first edition of Bayesian Computation with R (Use R) by Jim Albert availabl...
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A Brief Tour of the Trees and Forests
Tree methods such as CART (classification and regression trees) can be used as alternatives to logistic regression. It is a way that can be used to show the probability of being in any hierarchical group. The following is a compilation of many of the key R packages that cover trees and forests. The goal here is to simply give some brief example...
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Will Mu Go Out With Median
True story (no really, this did actually happen). While in grad school one of the other teaching assistants was approached by one of the students and was asked “will mu go out with median?” The teaching assistant thought the play on words was pretty funny, laughed, and then cluelessly walked away. All of us other grad students were su...
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Hey, I Just did a Significance Test!
I’ve seen it happens quite often. The sig test. Somebody simply needs to know the p-value and that one number will provide all of the information about the study that they need to know. The dataset is presented and the client/boss/colleague/etc invariably asks the question “is it significant?” and “what’s the correlation?”. To quote R...
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Latent Class Modeling Election Data
Latent class analysis is a useful tool that is used to identify groups within multivariate categorical data. An example of this is the likert scale. In categorical language these groups are known as latent classes. As a simple comparison this can be compared to the k-means multivariate cluster analysis. There are several key differences betwee...
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Software Packages for Graphs and Charts
Graphs can be an important feature of analysis. A graph that has been well designed and put together can make summary statistics much more readable and increase the interpretability. It also makes reports and articles looks more professional. There are many software packages that are available to design great graphs and charts. This seems to be...
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Using R to Produce Scalable Vector Graphics for the Web
Statistical software is normally used during the analysis stage of a project and a cleaned up static graphic is created for the presentation. If the presentation is in web format then there are some considerations that are needed. The trick is to find ways to implement those graphs in that web format so the graph is of the highest possible qual...
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Some Common Approaches for Analyzing Likert Scales and Other Categorical Data
Analyzing Likert scale responses really comes down to what you want to accomplish (e.g. Are you trying to provide a formal report with probabilities or are you trying to simply understand the data better). Sometimes a couple of graphs are sufficient and a formalize statistical test isn’t even necessary. However, with how easy it is to conduct s...
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Imputing Missing Data With Expectation – Maximization
It can be fairly common to find missing values in a dataset. Having only a few missing values isn’t generally a problem and those records can be deleted listwise. In other words the entire record is simply removed from the analysis. The problem is even with a limited amount missing data, that can translate into a significant number of records t...
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JSM 2013 – Monday
I am currently attending the 2013 Joint Statistical Meeting in Montreal. I will try to share a few if the things that I take away each day. Last night (Monday) I attended the JSM keynote speaker with Nate Silver and it proved to be a very interesting discussion. Silver is best known for his work on http://www.fivethirtyeight.com. His speech ...
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