From mathematical models to millions of parcels
Interview with Ellen Duijzer-Dibbits (AM’10) by Diana Dalenoord (UT Alumni Officer).
For Ellen Duijzer-Dibbits, an alumna of the University of Twente’s Bachelor's programme in Applied Mathematics, it became clear early on that she enjoyed logical thinking and solving complex puzzles. At school, she found mathematics fascinating, but she was also interested in programming and the cryptography behind online banking. In the end, however, she decided not to pursue the purely theoretical or computer science side of the field. Instead, she wanted to see the real-world impact of her work.
After completing her Bachelor's degree in Enschede, Ellen continued with a Master's degree at Eindhoven University of Technology, as the specialisation she was looking for was not available in Enschede at the time. She regretted having to leave, as she had thoroughly enjoyed her student years in Twente. "In Enschede, I had really built up my social life," she says. "That happens naturally during your Bachelor's degree. In Eindhoven, it was quite different." Many of her closest friends today are still people she met during her time as a student in Enschede.
The power of optimisation
During her Master's programme, Ellen discovered where her real interest lay: optimisation challenges within the business world. She deliberately chose additional courses in this area and realised that this was what truly excited her. "I wanted to work in industry and understand why you do something. Optimisation was really my thing."
Her interest had actually begun during her Bachelor's graduation project at the University of Twente. Together with Marjan van der Velde and Bert Kiewiet, she worked on a real-life assignment for the AMC involving children with a neuromuscular disorder. The aim was to develop a more efficient schedule for medical examinations and diagnostic procedures, minimising the burden on young patients. "Children had to come to hospital for several different examinations, which was naturally quite demanding. We investigated how all their appointments could be scheduled on a single day, so that ideally they could also receive their results before going home."
For Ellen, this was a defining moment in her studies. She saw how mathematical modelling could have a genuine societal impact. "It really gave you the feeling that mathematics adds value. That was incredibly rewarding."
The project was supervised by Nelly Litvak and Nicky Kortbeek and left a lasting impression on her. She especially appreciated the opportunity to work on a genuine real-world assignment while still an undergraduate.
Learning to truly understand problems
According to Ellen, her time in Twente provided her not only with subject knowledge but, more importantly, with a way of thinking. Analysing problems, asking the right questions and reducing an issue to its core are still fundamental to the way she works today. "In Twente, I learned how to translate problems into mathematical formulas and, first of all, how to determine what the real problem actually is. Sometimes a client or colleague thinks the issue lies in one place, but after asking more questions, it turns out that something entirely different is causing it." She still relies on this analytical approach every day. Interestingly, she often returns to a very traditional method.
From consultancy to bol
After graduating, Ellen deliberately chose a career in industry. She wanted her work to contribute to improvements in society and to see the direct impact of her analyses. During an internship as a Supply Chain Specialist at a manufacturing company, she discovered just how important it is to keep improving processes continuously. "Sometimes a solution works perfectly for a particular situation, but later it suddenly no longer does. Then you have to analyse the situation again and improve it."
She eventually joined bol as a consultant, working on practical, business-focused projects. When the opportunity later arose to become a data analyst at bol itself, she did not have to think twice.
Solving logistics puzzles
Today, Ellen works as a data analyst within bol’s logistics department. She focuses on challenges related to distribution centres and warehouses. Her work revolves around capacity, processes and optimisation.
Sustainability is also becoming increasingly important. Ellen investigates ways to reduce the use of cardboard and explores how data can help make logistics processes more efficient. In doing so, she always looks beyond a single isolated problem. "If you solve a bottleneck in one part of the process, a new problem may emerge further down the line. That’s what makes the work so challenging, because ideally you want a solution that continues to work in the long term."
It is precisely this combination of problem-solving, analysing and improving that motivates her. In warehousing, everything revolves around optimising the flow of parcels while at the same time taking account of disruptions elsewhere in the process.
Right where she belongs
After many years in the field, Ellen is certain that logistics is where she belongs. The combination of analytical thinking, collaboration and visible impact suits her perfectly.
Her working environment also plays an important role. She enjoys being part of a team where she feels at home, values the flexibility she is given and is even able to cycle to work. That balance means she continues to see plenty of opportunities and challenges in her role as a data analyst.
Ellen during the UT Twentse Wiskunde Estafette 2025