Beginning analysts and data scientists often ask: “how does one remember and master the seemingly endless number of classifier metrics?” My concrete advice is: Read Nina Zumel’s excellent series on scoring classifiers. Keep notes. Settle on one or two metrics as you move project to project. We prefer “AUC” ...

Short form: Win-Vector LLC’s Dr. Nina Zumel has a three part series on Principal Components Regression that we think is well worth your time. Part 1: the proper preparation of data (including scaling) and use of principal components analysis (particularly for supervised learning or regression). Part 2: the introduction of y-aware ...

We are pleased to announce a new free e-book from Manning Publications: Exploring Data Science. Exploring Data Science is a collection of five chapters hand picked by John Mount and Nina Zumel, introducing you to various areas in data science and explaining which methodologies work best for each. Exploring Data ...

geom_step is an interesting geom supplied by the R package ggplot2. It is an appropriate rendering option for financial market data and we will show how and why to use it in this article. Let’s take a simple example of plotting market data. In this case we are ...

This article is a demonstration the use of the R vtreat variable preparation package followed by caret controlled training. In previous writings we have gone to great lengths to document, explain and motivate vtreat. That necessarily gets long and unnecessarily feels complicated. In this example we are going to show ...

It is often said that “R it its packages.” One package of interest is ranger a fast parallel C++ implementation of random forest machine learning. Ranger is great package and at first glance appears to remove the “only 63 levels allowed for string/categorical variables” limit found in the Fortran randomForest ...

Some readers have been having a bit of trouble using devtools to install WVPlots. I thought I would write a note with a few instructions to help. These are things you should not have to do often, and things those of us already running R have stumbled through and forgotten ...

Just a “heads-up.” I’ve been editing a two-part series Nina Zumel is writing on some of the pitfalls of improperly applied principal components analysis/regression and how to avoid them (we are using the plural spelling as used in following Everitt The Cambridge Dictionary of Statistics). The series is ...

vtreat cross frames John Mount, Nina Zumel 2016-05-05 As a follow on to “On Nested Models” we work R examples demonstrating “cross validated training frames” (or “cross frames”) in vtreat. Consider the following data frame. The outcome only depends on the “good” variables, not on the (high degree of ...

We have been recently working on and presenting on nested modeling issues. These are situations where the output of one trained machine learning model is part of the input of a later model or procedure. I am now of the opinion that correct treatment of nested models is one of ...

Nina Zumel has donated some time to greatly improve the vtreat R package documentation (now available as pre-rendered HTML here). vtreat is an R data.frame processor/conditioner package that helps prepare real-world data for predictive modeling in a statistically justifiable manner. Even with modern machine learning techniques (random forests, ...