There are important discussions nowadays about data modeling, to choose between the “two cultures” (as mentioned in Breiman (2001)), i.e. either econometrics models or machine/statistical learning models. We did discuss this issue recently in Econométrie et Machine Learning (so far only in French) with Emmanuel Flachaire and Antoine Ly. One argument often used by econometricians is the interpretability of econometric models. Or at least the attempt to get an interpretable…
I often need to work with many variables at a time in SAS, but I don’t like to type all of their names manually – not only is it messy to read, it also induces errors in transcription, even when copying and pasting. I recently learned of an elegant and efficient way to store multiple […]
In my Serious Stats blog I have a new post on providing CIs for a difference between independent R square coefficients.You can find the post there or go direct to the function hosted on RPubs. I have been experimenting with knitr but can't yet ge...
In my Serious Stats blog I have a new post on providing CIs for a difference between independent R square coefficients.You can find the post there or go direct to the function hosted on RPubs. I have been experimenting with knitr but can't yet ge...
Theoretical Background Many statisticians and data scientists use the correlation coefficient to study the relationship between 2 variables. For 2 random variables, and , the correlation coefficient between them is defined as their covariance scaled by the product of their standard deviations. Algebraically, this can be expressed as . In real life, you can never […]
Following my post of yesterday about the missing condition in Lynch’s R code, Gérard Letac sent me a paper he recently wrote with Luc Devroye on correlation matrices and copulas. Paper written for the memorial volume in honour of Marc Yor. It considers the neat problem of the existence of a copula (on [0,1]x…x[0,1]) associated […]
Quite a coincidence! I just came across another bug in Lynch’s (2007) book, Introduction to Applied Bayesian Statistics and Estimation for Social Scientists. Already discussed here and on X validated. While working with one participant to the post-ISBA softshop, we were looking for efficient approaches to simulating correlation matrices and came [by Google] across the […]
A question recently posted on X Validated by Antoni Parrelada: given two arbitrary cdfs F and G, how can we simulate a pair (X,Y) with marginals F and G, and with set correlation ρ? The answer posted by Antoni Parrelada was to reproduce the Gaussian copula solution: produce (X’,Y’) as a Gaussian bivariate vector with […]
Emil Johansson, a Chemical Engineering student currently living in Gothenburg, Sweden made a beautiful visualisation of a well known event …Continue reading →
