Staff Data Scientist - Experimentation

Wallapop; Barcelona; Híbrido; EUR 110.000 - 160.000; Jornada completa

Ventajas ofrecidas por este puesto de trabajo

Generous learning budget

Private Health Insurance

Flexible working hours

Relocation package

26 holidays per year

Top hardware

Descripción de la vacante

Wallapop in Barcelona is seeking an experienced Experimentation lead to own the evolution of our experimentation practice. You will define standards, improve rigor, and help product teams make evidence-based decisions.

You will partner with Product, Engineering, Data Science, Analytics and leadership to ensure experiments are designed, executed, and analyzed consistently, acting as hands-on expert and internal consultant.

Formación

• 8+ years in data science, product analytics, or causal inference.
• At least 4 years deeply focused on experimentation (design, inference, A/B testing).
• Strong SQL skills and experience with Python or R.

Responsabilidades

• Define Wallapop's experimentation strategy and standards.
• Own methodology to reduce decision latency using advanced techniques.
• Coach PMs and analysts on hypothesis development and metrics.
• Build experimentation curriculum and playbooks.
• Improve infrastructure and data practices for experimentation.
• Design approaches for search ranking, recommendations, and monetization.

Conocimientos

Leadership

Experimentation

Communication

Stakeholder management

Herramientas

SQL

Python

R

Descripción del empleo

Wallapop is a Barcelona based scale-up driven by the purpose to empower people to embrace a more conscious and human way of consumption. We believe in a world where collaborative economy is mainstream. This is what drives us.

The Challenge

We are seeking an experienced Experimentation lead who will own the evolution of Wallapop's experimentation practice. This person will define the company's experimentation standards, improve statistical rigor, increase the speed and quality of product decisions, and help Product teams adopt a culture of evidence-based decision making.

You will partner closely with Product, Engineering, Data Science, Analytics, and Executive leadership to ensure experiments are designed, executed, analyzed, and interpreted consistently across the organization. You will be both a hands‑on expert and an internal consultant, helping teams answer critical questions about marketplace growth, personalization, search, discovery, trust & safety, monetization, and seller experiences.

What You Will Do

• Experimentation Strategy: Define Wallapop's experimentation vision and roadmap, establish company-wide standards, create frameworks for experiment prioritization, and develop guardrail metrics and governance.
• Statistical Excellence: Own methodology across the company and introduce advanced techniques (CUPED, sequential testing, network effect measurement, marketplace methods, quasi-experimental designs, and incrementally measurement) to reduce decision latency.
• Product Partnership & Enablement: Act as a strategic advisor and coach to Data Analysts, Data Scientists, and PMs on hypothesis development, experiment design, and success metrics to raise overall experimentation maturity.
• Education: Build Wallapop's experimentation curriculum, deliver training programs for PMs, Designers, Engineers, and Analysts, and establish playbooks and office hours.
• Platform & Tooling: Partner with Data Engineering and Analytics Engineering to improve infrastructure, evolve Amplitude Experiment data practices, and define quality standards for exposure logging.
• Marketplace Optimization: Design experimentation approaches for search ranking, recommendations, personalization, marketplace liquidity, supply-demand dynamics, seller growth, trust & safety, and ads monetization.

What We’re Looking For

• Technical Expertise:8+ years of total experience in data science, product analytics, or causal inference, including at least 4 years deeply focused on experimentation (experimental design, statistical inference, A/B testing, and variance reduction).
• Tooling & Code: Strong SQL proficiency along with experience using Python or R.
• Product Partnership: Proven ability to partner directly with Product organizations and influence senior stakeholders using strong business judgment.
• Leadership: Demonstrated success building experimentation cultures, experience coaching PMs and analysts, and excellent communication skills.

What Would Be A Plus

• Experience in Amplitude
• Experience working in marketplaces, e-commerce, consumer internet, or two-sided platforms.
• Experience with recommendation systems or search systems.

Do note that all our jobs are Barcelona based. We follow a hybrid model where flexibility rules. We commit to a minimum of 6 days per month in the office. Each team self-organizes to decide on cadence and in-person/remote rituals.

Wallapop is an equal-opportunity employer. We celebrate diversity and are committed to creating an inclusive environment for all employees as we want Wallapop to be a place for everyone.

We sponsor visa processes for international candidates when applicable and provide legal & admin support along the process combined with a competitive relocation package.

Additionally to the opportunity to contribute to an agile product set up and work together towards achieving our meaningful mission, we offer the following

Perks & Benefits

• Generous individual learning budget of 2K per year
• Free office meals, lunch selection from different providers
• Group and individual English, Catalan & Spanish lessons as part of our working day
• Private Health Insurance with Alan
• Flexible working hours + intensive Fridays
• Flexible remuneration to deduct from gross salary (kindergarten/food/transport check)
• Gym & Wellness plan, including physiotherapist in the office
• Generous referral Program & Charity Donation
• Bonus for weddings & newborns
• Monthly product advantages (Wallapop Club)
• Work anniversary Gifts and Birthday Surprises
• Contribution towards your WIFI in your monthly payroll
• One-off payment based on compensation package to go towards setting up your home office
• Relocation package (monetary support and legal advice) and visa sponsorship, if applicable
• 26 holidays per year
• TOP hardware of your choice (latest Apple or Windows)

What does the hiring process for this position look like?

Please, note that all interviews take place remotely over hangouts.

Intro Call - run by talent acquisition, focus on providing more information about the role and the company as well as going over your experience, motivation, and expectations. This usually takes 45-60 minutes.

Task - you will be assigned a task to submit within 5 up to 7 days where you will be able to showcase your expertise and technical skills required for the role.

Expertise Interview - run by the hiring team, focus on the required core skills and the ability to deliver in a given context. This usually takes 60-90 minutes.

Stakeholder Interview - run by relevant stakeholders reflecting the reality of the context of the role, focus on the ability to collaborate & deliver in a cross-functional set-up. This usually takes 60 minutes.

Culture Interview - run by culture interviewers, focus on adherence to Wallapop's purpose and business proposition. This usually takes 60 minutes.

Offer - should you be the right candidate, your offer will be discussed over a call with talent acquisition and then be confirmed in writing.