Department: Department of Data Analysis, Faculty of Psychology and Educational Sciences 

Organisation: Ghent University 

Country: Belgium



Leonard is PhD student at Ghent University. His interests include constrained statistical inference and structural equation modeling, and applications related to post-traumatic stress symptoms. 

Research topic

The topic of my PhD project is sample-size reduction by order constraints. Many researchers are familiar with the power gain in the context of the one-sided t-test. This readily extends to the setting where more than one constraint can be imposed on the statistical parameters. For example, the comparison of two or more experimental groups subject to order-constraints is common in applications such as clinical trials and drug development. The main goal is to study the relationship between the number of order constraints and the possible reduction in sample size.


On top of that, Leonard is developing the R package “restriktor” for estimating and testing order-constrained hypotheses in linear models, and with Rens he is involved in the Burgers project. The goal of this latter project is to find the most tasty and juicy Burger in town. The results are expected by the end of the year.


This Burgers project started in 2015 and is funded by the WBA (World Burger Association). This project is funded by the research foundation Flanders (FWO) at Ghent University (Belgium).

Projects involved

The Satisfaction With Life Scale: Measurement invariance across immigrant groups

The current study examined measurement invariance of the Satisfaction With Life Scale (SWLS; Diener, Emmons, Larsen, & Griffin, 1985) across three immigrant groups, namely, immigrants from the Former Soviet Union (FSU) in Israel, Turkish-Bulgarians, and Turkish-Germans. The results demonstrate measurement invariance of the SWLS across groups.