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Principal Data Scientist

London
Posted about 18 hours ago
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In short

As a Principal Data Scientist specializing in Personalization and Customer Algorithms, your mission is to set the strategic direction for customer modeling across On. You will lead high-impact initiatives to architect, train, and deploy personalization algorithms that deliver direct, measurable impact to our business and customers. Operating at the intersection of technology, product management, and commercial strategy, you will simplify technical complexity, navigate an evolving technology landscape, and partner with key product and technology partners to ensure we build algorithms that solve the right problems for our global customer base.

Your mission

  • Chart the vision for personalization and customer-level algorithms, ensuring all projects align seamlessly with On’s broader commercial goals and north star tech strategy.
  • Lead complex initiatives to design, train, and deploy batch and real-time machine learning models into well governed production environments.
  • Partner closely with Product Management and external Tech Partnerships to deeply understand core business challenges and design algorithms that directly solve high-impact customer needs.
  • Focus relentlessly on driving quantifiable business outcomes and customer value across every touchpoint, from web and app to personalized customer messaging.
  • Evaluate how we adopt and integrate changing commercial technologies and partner platforms.
  • Break down complex data science architectures and machine learning concepts to bring cross-functional leadership, product teams, and business partners along on the journey.
  • Act as a core technical authority on wider-On decisions, establishing standards for real-time model training, MLOps infrastructure, and algorithmic QA metrics.
  • Mentor and guide data science and engineering talent across the organization, fostering high technical standards and a culture of continuous learning.

Reasons to use Rodeo

I’m in my final year doing Economics and I don’t know whether to apply for grad schemes now or do a masters first. What do you think?

Honest answer — it depends on where you want to end up. A lot of top grad schemes (Big 4, civil service, banking) don’t need a masters. Let’s look at the ones you’d be competitive for now, and we can decide if a masters actually adds anything.

Also worth knowing: most autumn 2026 applications are open now. Timing matters more than you think.

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Grad scheme, placement, apprenticeship? Not sure what you want yet — that's fine. Your agent talks it through with you and turns "I have no idea" into a shortlist.

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Graduate Consultant — 2026 Scheme

PwC·London, UK
£35,000/yr

Why you're a good match

Strong

Your economics background and your summer at a regional bank line up with what PwC looks for on the consulting scheme. Applications close in four weeks.

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It searches the market for you

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Why you're a good match

You’ve got the grades and the economics background, and your bank internship is exactly the experience this scheme looks for. Apply soon — deadlines close within the month.

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Strong

Experience fit

Your summer at the bank plus your econometrics coursework map directly to the day-one responsibilities on this scheme — client modelling, market briefings, and deal support.

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Strong

Only hits

No noise. No "maybe this fits." Just roles with a clear explanation of why they're right — and where to focus when applying.

Your story

  • You have 10+ years of experience in building and shipping personalization engines, recommendation systems, and customer-level predictive models in a fast-paced D2C or E-commerce environment. This should include real-time model training, streaming data processing, and deploying low-latency machine learning models to production systems.
  • Proven track record of working side-by-side with Product Management and Tech Partnerships to translate ambiguous business challenges into solutions that have measurable large scale impact on key company KPIs.
  • Strong history of defining success metrics and validating customer impact through rigorous experimentation, A/B testing, and continuous feedback loops, in partnership with analytics and product teams.
  • Proven ability to lead complex, company-wide initiatives, influence senior business leaders, and drive strategic consensus across multi-disciplinary teams.
  • Advanced proficiency in Python, modern machine learning libraries, cloud environments (e.g., GCP, AWS), event-driven architectures (e.g., Kafka), and end-to-end MLOps practices, PyTorch, JAX & Tensorflow.
  • Experience in both deploying Generative AI in customer applications, and using generative AI to accelerate engineering delivery workflows.
  • Outstanding storytelling and presentation skills, with the ability to explain complex algorithmic behavior clearly to technical and non-technical stakeholders alike.

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What We Offer

On is a place that is centered around growth and progress. We offer an environment designed to give people the tools to develop holistically – to stay active, to learn, explore and innovate. Our distinctive approach combines a supportive, team-oriented atmosphere, with access to personal self-care for both physical and mental well-being, so each person is led by purpose.

On is an Equal Opportunity Employer. We are committed to creating a work environment that is fair and inclusive, where all decisions related to recruitment, advancement, and retention are free of discrimination.

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Skills

Personalization Engines
Recommendation Systems
Predictive Modeling
Real-time Model Training
Streaming Data Processing
MLOps
Python
GCP
AWS
Kafka
PyTorch
JAX
Tensorflow
Generative AI
A/B Testing
Strategic Leadership

Location

London, England, United Kingdom

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