Staff Data Scientist - Marketing at Preply (London, United Kingdom)Staff Data Scientist - Marketing

You’ll own Preply’s Marketing Mix Model end to end, the system that governs how we allocate marketing’s largest cost line, a 9-digit annual spend, across more than 30 markets and channels. You’ll partner directly with Finance to turn model output into the budget steering process, and with performance marketing to translate it into channel strategy. Within a year, you’ll have built a hierarchical model spanning our top markets, calibrated where possible against existing geo-experiments, and actively shaped the measurement roadmap by identifying, designing, and running the next tests needed to further calibrate it. The model’s channel-level marginal ROI will be a direct input into Finance’s 2028 budget planning.

What you’ll be doing:

• Own our Marketing Mix Model end to end: build it out, grow it from today's US model to a global, hierarchical setup, and turn it into an automated platform that steers budget allocation. Full ownership, not a support role.
• Turn MMM outputs into decisions: partner with performance marketing and finance to fold results into the budget process and guide teams on what they mean for strategy.
• Steer the testing roadmap that feeds the MMM: use its signals to pick which channels and questions to test, then design and run incrementality tests (geo experiments and other causal inference methods) to measure incremental ROI.
• Design a unified measurement framework that ties MMM, attribution, and incrementality together; MMM for big budget calls, incrementality-adjusted attribution for channel splits.
• Extend these causal inference methods beyond marketing, as a reusable foundation for how Finance and Product measure impact.
• Work with Data Engineering to build scalable pipelines and evolve our ETL as the modeling stack grows (e.g. adopting Databricks).

What you need to succeed:

• Hands-on MMM experience: you know that getting it right means testing multiple approaches before converging on a robust, defensible model.
• Strong grounding in Bayesian statistics, applied with rigor to MMM and causal inference.
• Built or owned at least one of: a marketing mix model, a geo-experimentation program, or another causal measurement system that steered real budget, with experience turning its outputs into action in language marketing and finance can use.
• Experimentation expertise: designing and evaluating incrementality tests and A/B experiments.
• Strong Python and SQL skills.
• Advanced written and verbal English.

Nice to have:

• PhD in mathematics, economics, statistics or similar, or equivalent applied experience
• Previous experience with causal inference techniques (e.g. geo-lift testing, causal impact, synthetic control, difference in differences, etc.)
• Previous experience with tools such as PyMC, Stan, Meridian, Robyn or similar
• Experience in marketplaces or digital businesses, ideally in performance marketing.

Why you’ll love it at Preply:

• An open, collaborative, dynamic and diverse culture;
• A generous monthly allowance for lessons onpreply.comPreply.com, Learning & Development budget and time off for your self-development;
• A competitive financial package with equity, leave allowance and health insurance;
• Not in Barcelona? We offer an attractive relocation package to join us in our Preply Barcelona Hub
• Access to free mental health support platforms;
• Access to Gympass-partnered wellness and gym centers throughout Spain to promote and support well-being and physical health;
• The opportunity to unlock the potential of learners and tutors through language learning and teaching in 175 countries (and counting!).

Our Principles

• Care to change the world - We are passionate about our work and care deeply about its impact to be life changing.
• We do it for learners - For both Preply and tutors, learners are why we do what we do. Every day we focus on empowering tutors to deliver an exceptional learning experience.
• Keep perfecting - To create an outstanding customer experience, we focus on simplicity, smoothness, and enjoyment, continually perfecting it as every detail matters.
• Now is the time - In a fast-paced world, it matters how quickly we act. Now is the time to make great things happen.
• Disciplined execution - What makes us disciplined is the excellence in our execution. We set clear goals, focus on what matters, and utilize our resources efficiently.
• Dive deep - We leverage business acumen and curiosity to investigate disparities between numbers and stories, unlocking meaningful insights to guide our decisions.
• Growth mindset - We proactively seek growth opportunities and believe today's best performance becomes tomorrow's starting point. We humbly embrace feedback and learn from setbacks.
• Raise the bar - We raise our performance standards continuously, alongside each new hire and promotion. We build diverse and high-performing teams that can make a real difference.
• Challenge, disagree and commit - We value open and candid communication, even when we don’t fully agree. We speak our minds, challenge when necessary, and fully commit to decisions once made.
• One Preply - We prioritize collaboration, inclusion, and the success of our team over personal ambitions. Together, we support and celebrate each other's progress.

Diversity, Equity, and Inclusion Preply.com is committed to creating an inclusive environment where people of diverse backgrounds can thrive. We believe that the presence of different opinions and viewpoints is a key ingredient for our success as a multicultural Ed-Tech company. That means that Preply will consider all applications for employment without regard to race, color, religion, gender identity or expression, sexual orientation, national origin, disability, age or veteran status.