Effectiveness & Experimentation Director

Dentsu is an integrated growth and transformation partner to the world's leading organizations. Founded in 1901 in Tokyo, Japan, and now present in over 145 countries and regions, it has a proven track record of nurturing and developing innovations combining the talents of its global network of leadership brands to develop impactful and integrated growth solutions for clients. Dentsu delivers end-to-end experience transformation (EX) by integrating its services across Media, CXM, and Creative while its business transformation (BX) mindset pushes the boundaries of transformation and sustainable growth for brands, people, and society.

iProspect is an important part of our world-class offering – a global digital-first end-to-end media agency. Its unmatched mix of media strategy and storytelling with digital expertise and audience knowledge defines the new territory of performance-driven brand building. By delivering human-centric solutions, iProspect accelerates growth for the world's most iconic brands. The iProspect team works across a network of more than 8000 media and performance specialists spread across 93 global markets.

We are hiring a Global Experimentation Director to lead the design, implementation, and governance of multi-market testing programs for a globally recognized automotive client. Sitting within the iProspect Global Effectiveness team, this role will focus on embedding a rigorous culture of experimentation across key markets, driving continuous learning, scalable automation, and strategic insight into media investment decisions. You’ll work at the intersection of media data and analytics, partnering with senior stakeholders and cross-functional teams to deliver high-impact experimentation frameworks that drive business outcomes.

• Oversee the global experimentation agenda, lead the rollout of testing frameworks, champion best-in-class methodologies, and enable local teams to execute, learn from, and scale successful experiments.
• Bring deep expertise in program management, measurement design, and effectiveness automation paired with strong collaboration skills.
• Lead the development and delivery of a global multi-market experimentation roadmap aligned to business priorities and performance KPIs.
• Design and implement structured repeatable testing frameworks (e.g. A/B geo experiments, incrementality studies) that drive marketing effectiveness and decision-making.
• Manage and scale centralized experimentation programs across regional and local teams, ensuring consistency, rigor, and local enablement.
• Build scalable processes and tooling (e.g. experimentation libraries, knowledge hubs, dashboards) to support efficient test execution and insight sharing.
• Partner with media data and analytics stakeholders to define testable hypotheses, ensure statistical rigor, and derive actionable insights.
• Work with Strategy & Planning teams on cross-channel synthesis of experimental results, translating complex outcomes into strategic media recommendations.
• Champion automation and knowledge-sharing initiatives to embed experimentation capabilities at scale.
• Drive education, training, and change management across stakeholders to improve measurement fluency and experimentation maturity.

• Solid experience in media effectiveness experimentation or marketing analytics with hands-on experience in at least one digital channel (SEO, PPC, Paid Social, Programmatic) within a global agency, consultancy, or client environment.
• Proven track record of managing and scaling multi-market experimentation programs that influence strategic media decisions.
• Deep understanding of testing methodologies (e.g. A/B, multivariate, geo-testing, holdouts, incrementality, brand lifts) and when to apply them.
• Strong program management skills able to coordinate cross-functional teams across markets and structurally deliver as well as communicate outcomes.
• Experience designing knowledge-sharing systems (e.g. centralized testing repositories, playbooks, reporting dashboards).
• Competency with measurement platforms and tools (GA4, Meta Lift, DV360, MMM) and analytical platforms (SQL, Power BI, Looker Studio, R/Python).

This is a permanent role. The team is based from either Manchester or London and works on a hybrid basis. As well as a competitive salary, you’ll enjoy a benefits package that you can tailor to your needs.

At Dentsu, we embrace diversity and inclusion, valuing the unique perspectives and contributions of every individual. We believe that diversity fuels creativity and innovation, benefiting our employees, partners, and communities. We welcome applications from all individuals regardless of race, ethnicity, nationality, religion, gender, gender identity, sexual orientation, age, disability, marital status, or any other protected characteristic. Beyond recruitment, we strive to create an environment where everyone feels respected, supported, and empowered to bring their authentic selves to work. We recognize the importance of work-life balance and are open to discussing flexible working arrangements for all roles. If you need reasonable adjustments due to a disability or medical condition during our recruitment process, please contact us, quoting the reference number of the role that you are applying for. Your needs will be handled with respect and confidentiality to ensure an inclusive and accessible experience.