Differential privacy was originally developed to facilitate secure analysis over sensitive data, with mixed success. It’s back in the news again now, with exciting results from Cynthia Dwork, et. al. (see references at the end of the article) that apply results from differential privacy to machine learning. In this article […]

Estimated reading time: 21 minutes

When we teach data science we emphasize the data scientist’s responsibility to transform available data from multiple systems of record into a wide or denormalized form. In such a “ready to analyze” form each individual example gets a row of data and every fact about the example is a column. […]

Estimated reading time: 25 minutes

In this note am going to recount “my favorite R bug.” It isn’t a bug in R. It is a bug in some code I wrote in R. I call it my favorite bug, as it is easy to commit and (thanks to R’s overly helpful nature) takes longer than […]

Estimated reading time: 9 minutes

It’s a folk theorem I sometimes hear from colleagues and clients: that you must balance the class prevalence before training a classifier. Certainly, I believe that classification tends to be easier when the classes are nearly balanced, especially when the class you are actually interested in is the rarer one. […]

Estimated reading time: 16 minutes

While skimming Professor Hadley Wickham’s Advanced R I got to thinking about nature of the square-bracket or extract operator in R. It turns out “[,]” is a bit more irregular than I remembered. The subsetting section of Advanced R has a very good discussion on the subsetting and selection operators […]

Estimated reading time: 13 minutes

Most data science projects are well served by a random test/train split. In our book Practical Data Science with R we strongly advise preparing data and including enough variables so that data is exchangeable, and scoring classifiers using a random test/train split. With enough data and a big enough arsenal […]

Estimated reading time: 8 minutes

Recently there has been some controversy over David Mumford’s Nature magazine invited obituary of Alexander Grothendieck being initially rejected on submission (see here and here). At issue was the attempt to explain the mathematical idea of schemes (one of Alexander Grothendieck’s most important contributions) to a non-mathematician audience. Professor Mumford […]

Estimated reading time: 12 minutes

As John mentioned in his last post, we have been quite interested in the recent study by Fernandez-Delgado, et.al., “Do we Need Hundreds of Classifiers to Solve Real World Classification Problems?” (the “DWN study” for short), which evaluated 179 popular implementations of common classification algorithms over 120 or so data […]

Estimated reading time: 16 minutes

Win-Vector LLC’s Nina Zumel has a great new article on the issue of taste in design and problem solving: Design, Problem Solving, and Good Taste. I think it is a big issue: how can you expect good work if you can’t even discuss how to tell good from bad?

Estimated reading time: 35 seconds

As we’ve mentioned on previous occasions, one of the defining characteristics of data science is the emphasis on the availability of “large” data sets, which we define as “enough data that statistical efficiency is not a concern” (note that a “large” data set need not be “big data,” however you […]

Estimated reading time: 15 minutes