Senior Experiment Data Scientist

Senior Experiment Data Scientist Join Sellforte as Experiment Data Scientist to design end-to-end experimentation, connect causal methods to MMM, and ship clear, actionable insights with our customers. We usually respond within a week Hello, and welcome to start your next journey with Sellforte! 👋 Sellforte helps retailers and consumer brands grow by making smarter, data-driven marketing decisions. We have been a data science company from day one: since 2017, our Marketing Mix Modelling (MMM) product has helped marketing teams and agencies understand what drives sales, evaluate media and promotions, and improve investment decisions. We are now entering a new phase. Our customer base is growing internationally, and our product is expanding beyond traditional MMM toward more granular optimisation, broader decision support, more automated workflows, and tighter integration of causal experimentation. For someone joining us now, this means a rare combination: a proven product and customer base, plus a fast-growing product area with real room to shape how it develops. 🚀 Why we’re hiring We are building a marketing measurement experimentation platform that allows our customers to run incrementality experiments, such as geo-lift and ad platform conversion lift tests, and feed the results back into our MMM models to validate and calibrate them. The goal is to make experimentation a natural part of how marketing teams make decisions, not a one-off analysis project. The platform is growing quickly, and there is real room to shape how it develops. You will help define how experiments are designed, run, analysed, and communicated to customers. Your work will reach real customer use cases quickly, as part of a team building the product and service together with customers. You will work alongside Kacper Solarski, our Lead Data Scientist currently responsible for the experimentation platform, as well as our customer-facing Data Scientists and the product and engineering people building the wider Sellforte platform. 🎯 What you will do as a Senior Experimentation Data Scientist You will help build the Sellforte experimentation platform end-to-end: from methodology and implementation to customer rollouts and continuous improvement. Build the experimentation platform Design and implement the core methodology for experiment design, power analysis, geo-splitting, and result validation Apply causal inference methods such as difference-in-differences, synthetic control, and related approaches where they fit the customer context Build data pipelines, analysis code, and outputs that turn raw experiment data into clear, trustworthy results Connect experiment outcomes back to our MMM models, so experiments can validate and calibrate the models our customers rely on Improve the platform so that experiments become easier to configure, run, interpret, and repeat Run experiments with customers Scope experiment opportunities together with customers and customer-facing teams Set up, configure, and run incrementality experiments such as geo-lift and ad platform conversion lift tests Validate results before delivery, identify limitations, and explain uncertainty clearly Help customers interpret results and translate them into practical marketing decisions Learn from feedback and keep improving the product Talk with customers and internal users about what works, what is confusing, and what should be improved next Turn feedback into product and methodology improvements 🌤️ What we hope from you We are looking for someone who combines statistical thinking with the ability to ship. You do not need to be a formal statistician, but you should be comfortable reasoning about uncertainty, bias, and causal claims. You do not need to be a software engineer, but you should be able to build maintainable analyses, data pipelines, and product-facing workflows that others can rely on. This is primarily a senior-level role. However, we are also open to exceptional mid-level candidates with strong hands-on experience or academic background in experiments, causal inference, or marketing incrementality measurement. Must-haves for this role: A solid foundation in statistics and causal inference , including concepts such as probability distributions, Bayesian inference, sources of bias, and quasi-experimental methods like difference-in-differences or synthetic control — you can reason about what data can and cannot tell you Strong hands-on Python skills and the pragmatism to turn ideas into working software Clear communication in English — you can explain complex topics to both technical colleagues and customers, and you are interested in how analytical results are used in real marketing decisions Location in the Helsinki/Espoo region , or willingness to relocate there. We offer relocation support to Finland. Nice-to-haves that can help you succeed: Experience analysing marketing incrementality tests , such as geo-lift experiments or ad platform conversion lift tests Experience with marketing technology, MMM, or customer-facing analytics products Experience building a product that scales : you have built and shipped something that real customers or users rely on, and you understand what it takes to keep it reliable as usage grows A proactive, collaborative mindset : you are comfortable taking responsibility for meaningful work while building together with a team Curiosity about improving workflows with modern AI tools in a practical, thoughtful way You do not need to tick every box to apply. If the role sounds like a strong match for your skills and direction, we would like to hear from you. 🌟 What Sellforte offers A meaningful product area with real impact. You will help build a new experimentation capability inside a product that already serves real customers. An open, low-hierarchy scaleup environment with warm, helpful colleagues and a shared ambition to build something valuable. 🚀 A truly international team with 10+ nationalities across multiple countries. A globally unique product built with modern data science and engineering practices. Opportunities for both technical and business growth. We actively build our product and data science culture through demos, knowledge sharing, and internal presentations. 🍕 Flexibility to find a work-life balance that suits you. We work in a hybrid model and expect regular collaboration at our Helsinki/Espoo office, especially in the beginning. Starting salary for senior candidates: €5,200-6,000 per month. Exceptional mid-level candidates may also be considered, with compensation adjusted based on experience. A wide range of benefits , including healthcare, lunch and activity benefits, five weeks of paid holiday from day one, phone and equipment, an options program, and home care services for sick children. 📅 How to apply If this sounds like the right next step for you, we would love to hear from you. We review applications and start interviews continuously, so we encourage you to apply as soon as possible. We may move forward with candidates already during the application period, and the posting may close early. Our recruitment process is designed to be transparent, collaborative, and meaningful. It typically includes: A 30-minute intro call with a Sellforte Data Scientist One or two interview sessions, including a conversational interview and a hands-on case exercise around experimentation and causal inference Opportunities to meet members of your potential future team We aim to get back to candidates quickly, typically within the same or the following week. Application deadline: June 30 If you have any questions about the role, feel free to reach out to Kacper Solarski at [email protected] . Team Data Science Locations Espoo, Finland Remote status Hybrid Espoo, Finland