Senior Data Scientist

Is this you?Titan Operating System S.L. (Titan OS), the Barcelona-based technology, entertainment, and advertising company, is looking for you!At TitanOS, we live by three core values:Make things happen - We take ownership, move fast, and deliver impactNo ego - We collaborate with respect and humility to reach shared goalsShow genuine passion - We love what we do and never stop learningCulture and environment are at the heart of our ethos. If the above resonates with you, keep reading because we believe you could be a perfect addition to our incredible team!Role overview: We are looking for a Senior Data Scientist to lead the development of predictive audience models for Titan OS, turning smaller seed and observed datasets into robust predictions of much larger customer populations for Connected TV advertising. This is a deeply technical role focused on statistics, sampling theory and machine learning, with a strong emphasis on representativeness, selection bias, population extrapolation and uncertainty.You will combine Titan OS first-party data with seed audiences and population-level datasets, owning the methodology from research and experimentation through validation, productionisation and model monitoring. Working closely with Data Engineering, Product, Commercial and Advertising teams, you'll be a senior technical voice responsible for challenging assumptions, communicating uncertainty and setting rigorous modelling standards with direct commercial impact.Key responsibilities:Build models that expand seed and sample audiences into high-value cohorts across the wider CTV populationApply weighting, calibration, MRP and hierarchical methods to extrapolate reliably from imperfect or non-representative samplesBuild propensity, classification, similarity, ranking and positive-unlabelled models to identify users with high affinity to a seed audienceCreate robust behavioural and contextual features from large-scale event data while preventing target leakage and instabilityDiagnose selection bias, coverage gaps and covariate shift, and communicate uncertainty in audience estimatesMeasure lift, precision/recall, calibration and stability using holdouts, temporal/geographic tests and observed campaign outcomesMove successful models into scalable pipelines with versioning, drift detection, monitoring and retrainingPartner with Product, Commercial and Engineering teams while setting rigorous modelling standards across the Data teamRequirementsWhat makes you a great fit:8+ years of professional experience in Data Science, Applied Statistics, Quantitative Research, Econometrics or a closely related fieldDeep statistical expertise in sampling theory, estimation, inference, probability, uncertainty quantification and experimental designStrong sample-to-population experience using techniques such as post-stratification, raking, calibration/propensity weighting, hierarchical models, or MRPHands-on ML lookalike experience using seed audiences, CRM/customer samples or known converters with propensity, classification, similarity/ranking or positive-unlabelled methodsAdvanced ML & feature engineering skills across GLMs, XGBoost/LightGBM, ensembles, embeddings and large-scale behavioural datasetsStrong model validation skills including lift/gains, precision@K/recall@K, probability calibration, A/B testing, stability and drift monitoringAdvanced Python & SQL skills with scikit-learn, pandas/NumPy and experience with large-scale cloud data platforms and production ML/MLOps are highly desirableStrong communication and quantitative foundations with a BS/MS in a relevant quantitative field; a PhD is advantageous but not requiredBenefitsReasons to apply:Competitive compensationPrivate health insuranceFriendly, diverse, and international work environmentOpportunity to work outside of your comfort zone and develop professionally in an exciting and fast-growing CTV industryChange the future of TV! A unique opportunity to join a well-funded, high-growth company in the early stages to help shape a product/business that will impact millionsIf you're excited about this position, don't hesitate to apply. We're waiting for you to join us! And if you want to know more about us, follow us on LinkedIn!