Staff Data Scientist - Marketing

We’ve just reached unicorn status with a $150M Series D, accelerating our vision to transform education through human-led, AI-enhanced learning. Today, 100,000+ tutors teach 90+ languages to learners in 180 countries - and we’re only getting started. As a category-defining company, we’re shaping what the future of learning looks like at global scale.

At Preply, we're growing a talented Data Team to empower top-notch decision-making across our organization. Our team collaborates closely with various other chapters - including product, business, and platform - leveraging analysis, experimentation, causal inference, and machine learning.

You’ll be embedded in cross-functional teams, partnering with our MarTech Product Manager, Marketeers, Tech Leads, and the Data Strategy team. Check out our Tech Radar to see the tools and technologies we love using at Preply!

About this role

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 on Preply.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!).