Archive for September 2019

Using the lasso for inference in high-dimensional models

Why use lasso to do inference about coefficients in high-dimensional models?

High-dimensional models, which have too many potential covariates for the sample size at hand, are increasingly common in applied research. The lasso, discussed in the previous post, can be used to estimate the coefficients of interest in a high-dimensional model. This post discusses commands in Stata 16 that estimate the coefficients of interest in a high-dimensional model. Read more…

An introduction to the lasso in Stata

Why is the lasso interesting?

The least absolute shrinkage and selection operator (lasso) estimates model coefficients and these estimates can be used to select which covariates should be included in a model. The lasso is used for outcome prediction and for inference about causal parameters. In this post, we provide an introduction to the lasso and discuss using the lasso for prediction. In the next post, we discuss using the lasso for inference about causal parameters. Read more…

Fun with frames

I have a confession. I wasn’t excited about the addition of frames to Stata 16. Yes, frames has been one of the most requested features for many years, and our website analytics show that frames is wildly popular. Adding frames was a smart decision and our customers are excited. But I have used Stata for over 20 years, and I have been perfectly happy using one dataset at a time. So I ignored frames.

Then I started working on an example for lasso using genetic data. I simulated patient data along with genetic data for each of 22 chromosomes saved in 22 separate datasets. Working with 23 datasets became cumbersome, so I thought I’d check out frames. I began by reading the manual and then tinkered with my genetic data. Along the way, I discovered a feature of frames that completely blew my mind. I’m going to show you that feature below, and I expect that it will blow your mind as well.

This blog post is not meant to be an introduction to frames. There is a detailed introduction to frames in the Stata 16 manual that will make you an expert. I simply want to show you some of the useful things that you can do with frames, including the following: Read more…