Production ML Data Scientist: Personalization & RL

Playtika; Warszawa; On-site; PLN 260,000 - 380,000; Full time

Job summary

Playtika in Warsaw, Poland, is seeking a Data Scientist Expert - Production ML to join the Data & AI department. You'll advance real-time personalization using Bayesian methods, scale models to millions of players, and own end-to-end improvements from research to production.

The role emphasizes independent problem finding, collaboration with engineers, BI, and product teams, and mentoring others, with a focus on statistical rigor and deploying impactful ML in production.

Qualifications

• M.Sc or PhD in Computer Science, Mathematics, Statistics, Engineering or a related field.
• 5+ years of relevant working experience, including significant production ML ownership.
• Experience taking statistically sophisticated models from prototype to production and operating them under real-world constraints.
• Experience with neural network architectures and diagnosing their behavior in probabilistic or decision-making contexts.
• Strong foundation in Multi-Armed Bandits, Bayesian methods, online learning, or related decision-making frameworks.
• Strong understanding of experimentation, causal inference and online decision systems evaluation.
• Proficiency in Python for production-grade code and SQL.
• Ability to communicate statistical reasoning to non-technical stakeholders.

Responsibilities

• Identify limitations in existing ML solutions and deliver provably correct, more efficient alternatives.
• Validate correctness of scaled solutions and redesign as needed for distributed execution.
• Own the full lifecycle of improvements from research to production deployment and impact measurement.
• Drive evolution and scalability of personalization and recommendation systems.
• Contribute to end-to-end data-driven research including problem definition, data collection, model development, evaluation, and deployment.
• Collaborate with engineers, BI, and Product to deploy solutions quickly and effectively.
• Mentor Data Scientists and ML Engineers and provide a technical reference on statistical and mathematical rigor.

Skills

Python

SQL

Bayesian methods

Reinforcement learning

NN architectures

Production ML ownership

Education

MSc or PhD in CS/Math/Stats/Engineering

Tools

PyBandits

PySpark

PyMC/NumPyro

MLOps / model serving

Claude/Cursor AI tools

Job description

Playtika in Warsaw, Poland, is seeking a Data Scientist Expert - Production ML to join the Data & AI department. You'll advance real-time personalization using Bayesian methods, scale models to millions of players, and own end-to-end improvements from research to production.

The role emphasizes independent problem finding, collaboration with engineers, BI, and product teams, and mentoring others, with a focus on statistical rigor and deploying impactful ML in production.