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, collaborating with economists, applied scientists, data analysts, product managers, software developers, data engineers, and commercial stakeholders. Responsibilities: - Design experimentation frameworks in new areas, focusing on key performance indicators, units of randomization, statistical power analysis, and variance reduction. - Design and execute experiments in complex cases, handling SUTVA violations and non‑trivial short‑term vs long‑term effect relationships. - Apply quasi‑experimental methods to observational data to establish causal relationships that inform product development and further experimentation. - 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 (required for Principal level). Qualifications: - Ph.D. in Economics with an emphasis on quantitative research methods and at least two years of post‑Ph.D. experience. - Deep expertise in experimentation and quasi‑experimental research methods (e.g., Double Machine Learning, difference‑in‑differences). - Strong scientific problem‑solving skills and ability to communicate analytical insights to technical and non‑technical audiences. - Proficiency in Python and SQL; experience with machine‑learning frameworks (scikit‑learn, PyTorch), Jupyter Notebooks, Airflow, DBT, PySpark, Databricks, and Git. - Experience estimating heterogeneous effects such as causal forests. - Regular use of AI‑based analytical tools and a mindset of continuous exploration. What We Offer: - 27 days of holiday per year (up to 30 days with seniority) plus 1 paid volunteering day. - Hybrid working model with up to 60 % remote work and the option to work abroad up to 30 days per year. - Employee share program. - Discounts: 40 % off Zalando fashion and beauty products, 30 % off Lounge by Zalando, and additional external partner discounts. - Relocation assistance (subject to prior agreement). - Family services, health and wellbeing options, mental health support, and coaching. - Development opportunities through a training platform and biannual peer‑to‑peer review.