Principal Applied Scientist / Lounge by Zalando (all genders)

Role: - Principal or Senior Applied Scientist at Zalando Lounge. Foster data‑driven decision‑making by designing experimentation frameworks and analysing complex A/B tests. Serve as expert on causal inference and statistical modelling. Collaborate with economists, applied scientists, data analysts, product managers, software developers, data engineers, and commercial stakeholders. - Lounge is an online shopping club for fashion and lifestyle in 13 European countries, the fastest‑growing sales channel of Zalando. Responsibilities: - Design experimentation frameworks in new areas, focusing on KPIs, units of randomisation, statistical power analysis and variance reduction. - Design and execute experiments in complex cases (e.g., SUTVA violations, short‑term vs long‑term effects). - Apply quasi‑experimental methods to observational data to infer causal relationships for product development. - Use economic modelling and first‑principle reasoning to guide business decisions. - Provide constructive scientific feedback and coach junior colleagues. - Set broad scientific roadmaps across the division (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 Notebooks, Airflow, DBT, PySpark, Databricks, Git. - Experience estimating heterogeneous effects (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 seniority) plus 1 paid volunteering day. - Hybrid working model up to 60 % remote; ability to work abroad up to 30 days per year. - Employee share programme. - Discounts: 40 % off Zalando fashion/beauty, 30 % off Lounge, external partner discounts. - Relocation assistance (subject to agreement). - Family services, health & wellbeing options, mental health support and coaching. - Development opportunities via training platform and biannual peer‑to‑peer review.