In section 10.9 of Regression and Other Stories, the authors introduce the idea of fitting the same model to many… Read more
Category: Regression
rms for the rest of us
For a few years now I’ve been chipping away at Regression Modeling Strategies by Frank Harrell. Between the exposition, the… Read more
Most useful tests for an ANCOVA model
In his book Regression Modeling Strategies, 2nd Ed, Frank Harrell provides a list of what he calls the “most useful… Read more
Using natural splines in linear modeling
Take a look at this scatterplot: It's clear there is a relationship between x and y, but the relationship is… Read more
Profile likelihood ratio confidence intervals
When you fit a generalized linear model (GLM) in R and call confint on the model object, you get confidence… Read more
Poisson regression – Ch 6 of Gelman and Hill
Chapter 6 of Gelman and Hill's Data Analysis Using Regression and Multilevel/Hierarchical Models presents an interesting example of Poisson regression… Read more
Partial Residuals and the termplot function
Earlier this year I taught an Intro to R Graphics workshop. While preparing for it I came across the termplot… Read more
Simulating responses from a linear model
Say you fit a model using R's lm() function. What you get in return are coefficients that represent an estimate… Read more
Exploring Unordered Contrasts in R
Contrasts in R determine how linear model coefficients of categorical variables are interpreted. The default contrast for unordered categorical variables… Read more
The Multilevel Model for Change (Ch 3 of ALDA) – revisited
In my previous post I talked about how to replicate the example in Chapter 3 of ALDA. It was mostly… Read more