
How to do stepwise regression in R?
You don’t.

New Preprint: Making “Null Effects” Informative
In February and March this year, I stayed at the Eindhoven Technical University in the amazing group with Daniël Lakens, Anne Scheel and Peder Isager, who are actively researching questions of replicability in psychological science. Over the two months I have learned a lot, exchanged some great ideas with the three of them – and…

phacking destroys everything (not only pvalues)
In the context of problems with replicability in psychology and other empirical fields, statistical significance testing and pvalues have received a lot of criticism. And without question: much of the criticism has its merits. There certainly are problems with how significance tests are used and pvalues are interpreted.1 However, when we are talking about “phacking”,…

Introduction to Bayesian Statistics (Slides in German)
Recently, I had the opportunity to give a lecture on Bayesian statistics to a semester of Psychology Master students at the University of Bonn. The slides, which are in German, I’d like to share here for interested readers.

How statistics lost their power – and why we should fear what comes next
This is an interesting article from The Guardian on “posttruth” politics, where statistics and “experts” are frowned upon by some groups. William Davies shows how statistics in the political debate have evolved from the 17th century until today, where statistics are not regarded as an objective approach to reality anymore but as an arrogant and…

Choosing CutOffs in Tests
My last blog post was on the difference between Sensitivity, Specificity and the Positive Predictive Value. While showing that a positive test result can represent a low probability of actually having a trait or a disease, this example used the values of Sensitivity and Specificity as preknown input. For established tests and measures they indeed…

“Statistics is in a mess.”

ASA statement on pValues: Improving valid statistical reasoning
A lot of debate (and part of my thesis) revolve around replicability and the proper use of inferential methods. The American Statistical Association has now published a statement on the use and the interpretation of pValues (freely available, yay). It includes six principles and how to handle pValues. None of them are new in a theoretical…

Birth Rates and Life Expectancy
Bad enough, that we have to read und hear current failures of thought by right wing populists (article in German only) and many relativizations (comments in German only). It seems like 70 years of History class did not help to stop utter racism in public debate. What, however, sparked my interest was the question what correlations…

Sorting Data independently before Regression
This thread on StackExchange is circling around my Twitter timeline today and I couldn’t resist sharing it here: Suppose we have data set (X_i, Y_i) with n points. We want to perform a linear regression, but first we sort the X_i values and the Y_i values independently of each other, forming data set(X_i, Y_j). Is…