Senior Data Scientist

ZappiStore; Greater London; On-site; GBP 100,000 - GBP 130,000; Full time

Job summary

A leading market research company based in London is seeking a Senior Data Scientist to spearhead the development of predictive models for ad effectiveness and product success. The ideal candidate should hold a PhD in a relevant field and demonstrate strong problem-solving skills, particularly in experimental design and data interpretation. Responsibilities include shaping data collection and designing validation frameworks to ensure model accuracy in challenging scenarios. The role comes with a generous salary package and a commitment to diverse and inclusive company culture.

Benefits

Generous PTO policy

Private medical healthcare cover

Flexible working arrangements

Free lunch in the office Tuesday-Thursday

Tailored personal development through training

Qualifications

• PhD or equivalent depth in ML, statistics, computational social science, or similar.
• Evidence of solving complex problems without existing solutions.
• Ability to design experiments and communicate across disciplines.

Responsibilities

• Own the modelling approach for various domains like Advertising and Innovation.
• Design validation frameworks to measure model performance.
• Shape data collection process to enhance predictive models.

Skills

Machine Learning

Statistical Analysis

Experimental Design

Data Interpretation

Communication Skills

Education

PhD in ML, Statistics, or related field

Job description

Senior Data Scientist

Application Deadline: 26 February 2026

Department: Engineering

Employment Type: Full Time

Location: London, UK

Compensation: £100,000 - £130,000 / year

Description

We're trying to predict how consumers will respond to ads and product concepts before companies spend millions producing them. We’re aiming to go well beyond simple LLM wrappers into actual predictive models trained on real survey data, validated against real market outcomes.

It's a significant challenge. The data is multi-modal and mixed qualitative and quantitative. The validation requirements are strict. Many of our competitors make vague AI claims with no published accuracy metrics. We'd rather be honest about what works and what doesn't.

We need someone who can push the research forward.

What You'd Actually Be Doing

You'd own the modelling approach for one of three domains — Advertising (predicting ad effectiveness), Innovation (forecasting product success), or Tracking (brand health dynamics).

You won't just be handed a dataset and told to find patterns. We're significantly investing in custom-designed surveys built specifically to train these models. You'd be shaping what data we collect, not just how we interpret it.

That means thinking through questions like: What stimulus variations do we need to capture the full distribution of ad quality? How do we ensure proper category and demographic balance? What response patterns actually predict market outcomes? The data asset itself is part of what you're building.

Some of the harder modelling problems:

• Validation frameworks. We need to know exactly how well our models perform, and more importantly, where they fail. You'd design how we measure this.
• Respondent-level synthesis. Most synthetic approaches just predict top-level scores. We're trying to generate full synthetic respondent profiles — hundreds of variables per individual. Architecturally quite different from regression to a mean.
• Cold start. How do you predict response to a genuinely novel product category or ad format? Where can we use transfer learning?
• Multimodal inputs. Video, images, text, brand context — figuring out what features actually matter for predicting human response.

What We're Looking For

• PhD or equivalent depth in ML, statistics, computational social science, or similar. We want someone who's driven research, not just applied existing tools.
• Evidence you can solve problems that don't have existing solutions. Papers, repos, production systems — something that shows how you think.
• Interest in experimental design, not just model fitting. If thinking about what data to collect is as interesting to you as what to do with it once you have it, that's a good sign.
• Tolerance for messy data. If imperfect real-world data frustrates you more than it energises you, this probably isn't the right role.
• Strong fundamentals over framework knowledge. We care more about whether you understand why approaches work than which libraries you've used.
• Ability to communicate across disciplines. You'll work with research scientists who think in survey methodology terms. Translation skills matter.
• Budget to build the dataset properly. We're not trying to do this on the cheap. Custom data collection designed specifically for training predictive models.
• Historical data to learn from. Years of survey responses that inform what works — even if the pure training data needs to be purpose-built.
• Infrastructure that doesn't fight you. We've spent a lot of time building a data platform that lets data scientists actually test ideas quickly.
• Domain experts. Research scientists with deep expertise in survey methodology and market research. You won't be figuring out the domain alone.

Benefits

• Three company-paid mental health days of rest per year (these are pre-scheduled, so the entire company can take the same days off regularly to reset)
• Generous PTO policy - Minimum of 20 days of paid time off per year, plus national holidays. Leave over 30 days requires manager and People team approval.
• Private medical healthcare cover
• Group risk, life & disability contributions
• Flexible working arrangements, including remote (unless otherwise specified)
• Thoughtfully designed offices to support both individual work and collaboration without interrupting others
• Wellbeing benefits such as free yoga and access to trained therapists / counsellors
• Enhanced parental leave policies
• Free lunch in the office Tuesday-Thursday
• Tax efficient pension contributions via salary sacrifice scheme
• Salary sacrifice cycle to work scheme
• Salary sacrifice nursery scheme
• Tailored personal development through training allowances, coaching, mentorship and career frameworks

Why join us?

We’ve been recognized as one of the hottest martech companies in 2022 by Business Insider and named Best Place to Work by Quirk’s Media for our engaging and inclusive workplace culture. We’re committed to both people and the planet.

Our belief in inclusion means we’re building an organisation of diverse individuals and helping brands eliminate cultural presumptions in their research. Read our Diversity Manifesto here.

We are a values and behaviours driven business and believe that Trust, Truth, Ownership, Ambition and Humility describe Zappi employees on our best day. This is how we strive to show up for our customers, for each other and for our communities.

Our commitment to minimise our impact on the environment means being honest with ourselves and transparent with you—about everything from carbon emissions to tree-planting initiatives. We achieved our goal of becoming Net Zero in 2021!

Zappi Company Culture Highlights

• Winner of Comparably's Award for Best Company for Women 2022
• Winner of Comparably's Award for Best Company Work-Life Balance 2022
• Winner of Comparably's Award for Best Company Compensation 2022
• Winner of Comparably's Award for Best CEO for Women 2022
• Winner of Comparably's Award for Best Company for Diversity 2022
• Winner of Comparably's Award for Best Company Culture 2022
• Winner of Comparably's Award for Best CEO 2022
• Winner of Comparably's Award for Best Happiness 2022
• Winner of Comparably's Award for Best Leadership Teams 2023
• Winner of Comparably's Award for Best CEOs for Diversity 2023
• Winner of Comparably's Award for Best Engineering Teams 2023
• Winner of Comparably's Award for Best Company Outlook 2023
• Winner of Newsweek’s Top 100 Most Loved Workplaces in the UK 2022 & 2023
• Recognised by Fast Company’s Best Workplaces for Innovators 2023
• Winner of Best Marketing Insights Platform in the MarTech Breakthrough Awards 2023 & 2024

Equal Opportunity

Zappi is an equal opportunity employer; our diversity is a major strength. We are committed to providing equal opportunities for all individuals, regardless of their race, gender, sexual orientation, disability, or any other characteristic protected by applicable laws.

We believe that a diverse and inclusive workforce fosters innovation, creativity, and success. Our hiring decisions are based solely on merit, qualifications, and abilities, ensuring fairness and equity throughout our recruitment process. We welcome applications from all backgrounds and encourage candidates from underrepresented groups to apply. Join our team and contribute to an inclusive environment where everyone's unique perspectives and talents are valued and respected.