Data Scientist, Marketing Mix Modelling

Do you want to build models that shape how ambitious brands invest in marketing? Are you motivated by combining Bayesian modelling, commercial understanding, and clear client advice?

At s360, you will own Marketing Mix Modelling engagements from the first data questions through to client-ready recommendations. Based in Barcelona and working with clients across the Nordics and the UK, you will help turn Meridian models into decisions clients can act on.

As our Data Scientist you will take ownership of Marketing Mix Modelling delivery from end to end. You'll work closely with clients, Digital Growth colleagues, account teams and measurement specialists to make sure every model is technically sound, commercially relevant and easy to understand. You will bring the business context into the model, raise issues early when a result looks off, and help the team deliver work that clients can trust and use.

Your main responsibilities will be:

• Model ownership: Build and sign off Meridian models end to end, covering KPI definition, geo-level design, prior selection, sampler settings, convergence and fit diagnostics.

• Client collaboration: Agree on data, priors, assumptions and expectations with clients before each build, then present the findings to senior marketing and finance stakeholders.

• Calibration and validation: Test model outputs against geo and holdout incrementality tests, and bring structured evaluation to results.

• Budget recommendations: Turn ROI, response curves, saturation and budget optimisation into clear recommendations clients can act on.

• Data and workflows: Manage data intake and validation with client teams, and run modelling workflows in Google Cloud / AWS / Microsoft Azure and Python Notebooks, e.g. Colab.

• Scoping and refreshes: Scope proposals and model refreshes for client engagements together with the Group Head of Measurement.

You will join s360's Measurement department as the go-to person for Marketing Mix Modelling, both with clients and inside s360. Most of your colleagues in Measurement build the tracking and data foundations that good models rely on, such as GA4, server-side setups and data quality. Your work starts after that: you decide how we build and calibrate our models, and you are the voice clients hear when we explain what the results mean.

You will have real influence on how MMM grows with s360, including how incrementality testing fits alongside it. You will also work closely with Google's Meridian team on many of our existing engagements.

Your day-to-day base will be our office at Norrsken House Barcelona, which you'll share with colleagues from several s360 teams.

We're looking for a Data Scientist with technical depth, commercial curiosity and the ability to make complex things simple. You're comfortable owning the full modelling process, you ask the hard questions about data and assumptions, and you explain uncertainty in plain language.

You’ll probably be a good fit if you recognise the following about yourself:

• Bayesian framework expertise: Hands-on experience with Bayesian Marketing Mix Modelling in Meridian, PyMC-Marketing or Robyn, including adstock, saturation and prior selection.

• Client-ready delivery: The ability to deliver Meridian models that hold up in front of the client without rework, with well-founded priors, clean diagnostics and a clear readout.

• Model diagnostics and judgment: Experience with convergence, posterior predictive checks and fit, plus the judgment to tell whether a result is plausible.

• Media understanding: A solid grasp of how media is bought and measured across search, social, TV and offline channels.

• Client communication: Conf…