Senior Data Scientist

Department: Data Science

Reporting to: Data Science Manager

Location: London or Amsterdam

Hybrid role: 3 days a week from the office & 2 days working from home

About this role The AI Growth team builds the AI systems that make JET's marketplace more relevant for millions of customers and partners across 14 countries. We develop JET's foundation model platform, train and serve embedding models for search and recommendations, and build the intelligent targeting systems that power personalised offers and push notifications.

As a Senior Data Scientist, you will own complex, multi-component ML solutions from problem framing through to production measurement. You will be the technical lead on your workstream — making and defending modelling decisions, designing evaluation frameworks, and shaping how the team approaches new problem classes. Working closely with ML Engineers and Data Engineers, your models will reach meaningful commercial scale and impact millions of customer journeys daily.

These are some of the key components to the position:

Own end-to-end ML projects from problem framing through to production deployment, defining approaches, managing trade-offs, and communicating findings to stakeholders

Produce technical design documents that guide modelling choices, weighing data availability, serving latency, interpretability, and long-term maintainability

Design and own LLM-based solutions for customer or partner representations, content personalisation, or recommendation, including training data curation and evaluation methodology

Build evaluation frameworks that link to business metrics, run well‑powered online experiments, and investigate offline‑to‑online performance gaps

Close the gap between offline model performance and online business impact through rigorous experimentation and measurement

Act as primary technical reviewer for junior colleagues, providing substantive, teaching‑oriented feedback that raises the team's overall standard

Collaborate with ML Engineers and Data Engineers to ensure models reach meaningful commercial scale across multiple markets

Shape technical direction across the AI stack, spanning search ranking, homepage personalisation, promotions intelligence, and foundation model applications

What will you bring to the team?

Several years of hands‑on data science experience owning ML systems end‑to‑end in production environments

Production‑quality Python skills and confident SQL for working with large‑scale data warehouses

Experience building offline evaluation frameworks from scratch, including metric selection, holdout strategy, leakage checks, and documented links to business metrics

Practical experience designing data pipelines for production models, including feature specification, lookback window rationale, and handling sparse data and cold‑start cases

Hands‑on experience with retrieval, ranking, or embedding‑based approaches in recommendation or personalisation contexts

Experience building evaluation frameworks for LLM‑based outputs, including quality dimensions, judge pipelines, and hallucination checks

Confidence with A/B test design at scale, including randomisation unit selection, statistical power calculations, and accounting for novelty effects

Strong written and verbal communication skills, able to translate complex modelling decisions into clear recommendations for technical and non‑technical audiences

An analytical problem‑solving mindset, comfortable with ambiguity and able to bring clarity to complex questions

Bonus skills:

Familiarity with causal inference or uplift modelling in e‑commerce or marketplace contexts

Parameter‑efficient fine‑tuning of large language models

Experience with ML orchestration or experiment tracking tooling

Inclusion, Diversity & Belonging No matter who you are, what you look like, who you love, or where you are from, you can find your place at Just Eat Takeaway.com. We’re committed to creating an inclusive culture, encouraging diversity of people and thinking, in which all employees feel they truly belong and can bring their most colourful selves to work every day.

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