Visiting the Dutchies: A Statistical Modeling Workshop

The modern scientific method has its origins in the 17th century and has been constantly developing throughout the centuries. And even though procedures may vary from one science to another a crucial part for all is the comparison of experimental data with theoretical predictions. To draw any conclusion and solve physical problems based on observation and theory one needs to develop a statistical model to connect the two. Therefore one of our supervisors professor Wouter Verkerke, who happens to be an expert on the matter, gave a 3-day workshop for both INSIGHTS and local PhD students at the Dutch National Institute for Subatomic Physics (Nikhef) in

As a Dutchman it was a welcomed excuse to travel back to my country and also revisit the institute where I used to work before my PhD. Most of ESRs arrived on the evening before the workshop. Because it had been while since we last saw each other we used the opportunity to catch up and exchange stories on our first few months. And to give the other ESRs some taste of the Dutch culture we did so whilst enjoying some drinks and “stamppot met rookworst” in the center of Amsterdam. I thought it would ease them in instead of throwing them in the deep with the raw herring and onions tradition. Maybe next time!

The next day we started our workshop which had a clear cut structure and a good build up in complexity and detail. In the morning Wouter gave us lectures on the theory and in the afternoon we got to apply the concepts with a set of exercises in RooFit, one of the most used statistical modeling software packages at CERN and the brainchild of David Kirby and Wouter himself. Throughout the workshop we learned about basic concepts such as typical probability density models, p-values and Likelihood Ratios to more advanced topics such as incorporation of nuisance parameters, unfolding and Effective Lagrangian Morphing.

The workshop was closed with a talk from former Nikhef PhD student Max Baak currently working at KPMG as chief data scientist. Because many PhD students and post-docs continue in industry or business Max was invited to give a talk on his experience at KPMG. He told us how he applied his knowledge acquired in academics and used some of his recent business cases as examples. Good to see what some of the non-academic possibilities are!

Kudos to Wouter Verkerke for giving us such a complete and clear picture of statistical modeling in particle physics including hands-on experience in RooFit. It was a great workshop and hopefully we can come back soon for a follow-up!



Meet the ESRs: Pim Verschuuren

Hi everybody!

My name is Pim Verschuuren and I am the ESR at Royal Holloway, University of London.

I am originally from the Netherlands where I acquired my bachelors and masters degree in Physics from Utrecht University. Utrecht is the fourth biggest city of The Netherlands and has a history that traces back to the Romans that laid the first foundations for the “Domstad”. However, nowadays Utrecht has become a modern and progressive city, culture and science play an increasingly important role and has a vibrant student life for both natives and internationals. But apart from housing all these aspects that I enjoyed whilst living there, it is also the place where I developed my inclination with particle physics.

During my studies I found my passion for particle physics as soon as during my bachelors. I therefore tried to submerge myself as much as possible with courses and research projects within this field and quickly came in contact with the organization that is the nexus of particle physics: CERN. The past few decades this combined effort of thousands of technicians, engineers and physicists from all over the world has proven to be very fruitful with the Higgs boson as the most recent crown jewel. I myself was lucky to contribute to both the ALICE and the ATLAS experiment where my biggest project entailed measurements of Higgs boson properties.

After multiple projects within particle physics at CERN I was convinced that a PhD in this field would be the right next step for me. But apart from the standard PhD characteristics like analysis of complex and abstract problems I was also looking for some additional specifics. More and more has machine learning become a part of varying parts of our society and the scientific community of CERN is no exception. I therefore sought a PhD that combines particle physics and the newest machine learning techniques to be part of this surge of innovation. And taking into account my love for traveling, working with a diverse group of scientists from all over the world and keeping the learning curve as steep as possible I came to the conclusion that a PhD in the INSIGHTS network was a perfect fit for me.

My main scientific subject will be on machine learning techniques in unfolding under the supervision of professor Glen Cowan from Royal Holloway, University of London. Just like with any scientific experiment the measuring devices in particle physics are never perfect. The measurements that should reflect nature perfectly actually give a convoluted picture specific to the measuring device. The whole game of unfolding is to take this convoluted picture and try to retrieve the true result that correctly reflects nature.

After the few events that we had with the network I feel even more excited and motivated to contribute to the INSIGHTS network. All of the other ESRs and supervisors clearly feel the same way and have already shown to be a great source of inspiration and creativity. With still a large part of the program ahead of me I look forward collaborating with all of them!