Most readers of this blog are likely familiar with the use of the ROC (Receiver Operating Characteristic) curve (or, at least, the area under that curve) for evaluating the quality of binary decision processes. One example of such a process is a binary classification model; another example is an A/B […]

Estimated reading time: 7 minutes

Introduction I’d like to discuss a simple variation of A/B testing in an engineering style. By “an engineering style” I mean: We will work a simulated example to see that the system works as claimed. We will exhibit examples of problems before trying to fix them. We will demonstrate all […]

Estimated reading time: 46 minutes

I would like to share a new article on some of the methods and pitfalls of time series forecasting: “A Time Series Apologia”. In it I work the seemingly simple problem of forecasting a noisy copy of sin(t). The purpose of the article is to demonstrate using ARIMA methods, and […]

Estimated reading time: 42 seconds

The standard way to estimate the an expected value of a population from a sample of values v1 … vn is to compute the average (1/n) sumi = 1…nvi. It is well known in statistics that for grouped data, there are other estimators that can have smaller expected square error. […]

Estimated reading time: 41 seconds

Introduction I would like to talk about the nature of supervised machine learning and overfitting. One of the cornerstones of our data science intensives is giving the participants the experiences of a data scientist in a safe controlled environment. We hope by working examples they can quickly get to the […]

Estimated reading time: 33 minutes

The core of our “statistics to English translation” series is Nina Zumel’s sequence of articles: “I don’t think that means what you think it means;” Statistics to English Translation, Part 1: Accuracy Measures Statistics to English Translation, Part 2a: ’Significant’ Doesn’t Always Mean ’Important’ Statistics to English Translation, Part 2b: […]

Estimated reading time: 55 seconds

I am conducting another machine learning / AI bootcamp this week. Starting one of these always makes me want to get more statistical commentaries down, just in case I need one. These classes have to move fast, and also move correctly. In this case I want to write about decomposition […]

Estimated reading time: 5 minutes

In our data science teaching, we present the ROC plot (and the area under the curve of the plot, or AUC) as a useful tool for evaluating score-based classifier models, as well as for comparing multiple such models. The ROC is informative and useful, but it’s also perhaps overly concise […]

Estimated reading time: 12 minutes

A client recently came to us with a question: what’s a good way to monitor data or model output for changes? That is, how can you tell if new data is distributed differently from previous data, or if the distribution of scores returned by a model have changed? This client, […]

Estimated reading time: 17 minutes

vtreat version 1.5.2 just became available from CRAN. We have a logged a few improvement in the NEWS. The changes are small and incremental, as the package is already in a great stable state for production use.

Estimated reading time: 36 seconds