Careers in Data – John on working in Tesco’s Supply Chain team

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John discusses his journey through Cambridge, his experience as a data analyst in Tesco’s Supply Chain team and why he chose to pursue a career in data.

Picture of John
John is 28, he grew up in Wakefield, West Yorkshire and then went to study at the University of Cambridge. John is now a Forecasting Data Analyst in the Supply Chain Team at Tesco which involves using data to build models to predict future customer behaviour and sales patterns. He loves problem solving and enjoys uncovering trends in data and building predictive models.

What did you do at Cambridge?

I graduated from Robinson College, Cambridge, in 2020 after spending 8 years studying there. My undergraduate degree was in Physical Natural Sciences specialising in Astronomy. I then studied for a PhD in Astronomy where my thesis was on the chemical composition of extrasolar planets.

Outside of studying, my time at Cambridge was mainly spent playing football. I played for the university team for 7 years & was lucky enough to go on multiple tours abroad while also representing the university at the world elite university football tournament in China. Additionally, I enjoyed supervising at Cambridge, teaching both the undergraduate Natural Science Maths course and the undergraduate Astronomy course.

Why did you decide to join Tesco Supply Chain?

During the final few years of my PhD, I realised that the part of the PhD I enjoyed the most was the process of researching and then subsequently presenting the results. I found the ideas creation stage, the writing of the code and the creation of figures to explain the results particularly rewarding.

Having discovered it wasn’t really the subject matter that interested me, more the general problem solving and analysis, I started thinking about careers outside of academia. The most obvious path was a career in data science/analysis as it would give me the structure and stability that academia couldn’t, while still allowing me to use my coding, statistical and mathematical skills to conduct research style projects.

I first heard about the possibility of working as a data scientist/analyst in the Supply Chain team at Tesco at a careers fair in Cambridge. The projects & models discussed really interested me and I decided it was definitely something I could see myself doing after completing my PhD. I subsequently joined Tesco in December 2020 once my PhD was finished.

What does a data analyst in Supply Chain do?

My day-to-day role is mainly separated into two parts: root causing & solving ad hoc issues with the forecasting model and working on a project which aims to improve the model’s accuracy. Addressing ad hoc issues usually involves querying national level sales & performance databases while also tracking the model’s output using SQL.

Working on a project usually comprises several stages. Initially we use SQL to query and establish the current strengths & areas of weakness in the particular section of interest in the model. Next we typically write code and create visualisations in Python to track how potential changes could improve the model’s performance. The last step involves running simulations written in MATLAB & Python to estimate how the company KPIs will behave if the suggested modifications were made to the live production model.

Most recently I finished a project which improved the accuracy of the part of the model which predicts on which day of the week shoppers will buy certain products. Accurately forecasting when sales will occur is vital to the business & the planet as it enables Tesco to maximise the availability of products for customers while reducing wastage. In fact, the project now prevents £8m worth of fresh food being wasted annually.

Picture of John's workspace

What do you enjoy most about the role?

I love the day-to-day problem solving and like the fact that the role both involves working on a main project in a similar but accelerated fashion to my PhD but also involves troubleshooting and solving much smaller problems. I also really enjoy Tesco’s emphasis on learning new skills.

Before I joined the team, I had only ever used MATLAB & Python for analysis; I have since had great support to not only improve my MATLAB & Python skills but also learn PySpark & SQL from scratch. Being able to work with a group of like-minded individuals is great, the atmosphere is fantastic. The Supply Chain team is a really fun environment both during and outside of the working day due to the plethora of extra-curricular activities open to all.

What advice do I have for students who are weighing up their career options?

Firstly, I would say it is okay to not know exactly what you want after you finish university. However, I would recommend using the University Careers Service and going to as many suitable careers fairs and events as possible – these give a really good insight into the opportunities out there. Secondly, a job in data science or data analysis could be perfect for anyone who really enjoys the problem solving and project orientated aspect of their STEM degree but is unsure about staying on in academia or doesn’t have a specific vocation in mind. Finally, don’t be worried or unsure about applying for many different roles. Actually, I often found going through the application process gave me a much clearer indication of whether I would enjoy the role or not.

  • John attended the Maths & Quant Finance Fair whilst at Cambridge, which is how he first spoke to Tesco Supply Chain about their job opportunities. Tesco Supply Chain will be back at our upcoming Graduate Jobs Fair on the 17th June, 1-3.30pm. They are also running a webinar on 24th June 1 – 1.45 looking at the theme of Sustainability in the Supply Chain. Register and sign up for a slot via Handshake.
A Day in the Life of a Data Analyst

John takes us through a typical day for him at work in the vlog below!

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