Principal Applied Scientist / Lounge by Zalando (all genders)

Role: - As a Principal or Senior Applied Scientist at Zalando Lounge, you will foster data-driven decision-making by designing experimentation frameworks and analysing complex A/B tests. You will serve as an expert on causal inference and statistical modelling, collaborate with economists, applied scientists, data analysts, product managers, software developers, data engineers, and commercial stakeholders. The team works within Lounge by Zalando, an online shopping club operating in 13 European countries. Responsibilities: - Design experimentation frameworks in new areas, focusing on KPIs, randomization units, statistical power analysis, and variance reduction. - Design and execute experiments in complex cases, addressing SUTVA violations and short‑term vs long‑term effects. - Apply quasi‑experimental methods to observational data to establish causal relationships for product development. - Use economic modelling and first‑principle reasoning to guide business decisions. - Provide constructive scientific feedback to peers and coach junior colleagues. - Set broad scientific roadmaps across the division and demonstrate scientific leadership (required for Principal level). Qualifications: - Ph.D. in Economics with emphasis on quantitative research methods and at least two years post‑Ph.D. experience. - Deep expertise in experimentation and quasi‑experimental methods (e.g., Double Machine Learning, difference‑in‑differences). - Strong scientific problem‑solving skills and ability to communicate insights to technical and non‑technical audiences. - Proficiency in Python and SQL; experience with ML frameworks (scikit‑learn, PyTorch), Jupyter, Airflow, DBT, PySpark, Databricks, Git. - Experience estimating heterogeneous effects (e.g., causal forests). - Regular use of AI‑based analytical tools and a mindset of continuous exploration. What We Offer: - 27 days holiday (up to 30 with tenure), 2 paid volunteering days. - Hybrid working model with up to 60 % remote, ability to work abroad up to 30 days per year. - Employee share program, 40 % discount on Zalando fashion/beauty products, 30 % discount on Lounge, external partner discounts. - Relocation assistance (subject to agreement), family services, health and wellbeing options, mental health support and coaching. - Development opportunities via training platform and bi‑annual peer‑to‑peer review.