Jörn Alexander Quent's notebook

Posts on my work

Finding a U-shape with Bayesian interrupted regression

The outset of the problem In one of my project, I’d like to show that there is a U-shape relationship between two variables. The traditional way to do this would be to fit a quadratic model and test whether the quadratic term is different from zero. However, Simonsohn (2018) among other correctly points out that evidence for a quadratic fit is not enough and there might be situations where the quadratic term is not zero but there is no true u-shape. Read more →