Staff Data Scientist (Experimentation)

TL;DR

Staff Data Scientist (Experimentation): Defining and evolving the company's experimentation standards and statistical rigor to improve product decision speed and quality with an accent on causal inference and variance reduction. Focus on implementing advanced statistical techniques like CUPED and sequential testing to optimize marketplace dynamics.

Location: Hybrid in Barcelona, Spain (Minimum 6 days per month in office). Relocation and visa sponsorship available.

Company

hirify.global is a Barcelona-based scale-up focused on empowering a conscious and human way of consumption through a second-hand marketplace.

What you will do

• Define the experimentation vision, roadmap, and company-wide standards for product decision making.
• Implement advanced statistical techniques including CUPED, sequential testing, and quasi-experimental designs to reduce decision latency.
• Act as a strategic advisor and coach for PMs, Analysts, and Data Scientists on hypothesis development and success metrics.
• Develop an experimentation curriculum, deliver training programs, and establish playbooks for the organization.
• Partner with Data Engineering to improve infrastructure and define quality standards for exposure logging.
• Design experimentation approaches for search ranking, personalization, marketplace liquidity, and ads monetization.

Requirements

• 8+ years of total experience in data science, product analytics, or causal inference.
• At least 4 years of deep focus on experimentation, A/B testing, and variance reduction.
• Strong proficiency in SQL and experience with Python or R.
• Proven ability to influence senior stakeholders and partner directly with Product organizations.
• Demonstrated success in building experimentation cultures and coaching other technical staff.
• Must be based in or be able to relocate to Barcelona, Spain.

Nice to have

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

Culture & Benefits

• Annual individual learning budget of €2,000 and language lessons (English, Catalan, Spanish).
• Private health insurance (Alan) and gym/wellness plan with an in-office physiotherapist.
• Flexible working hours, intensive Fridays, and 26 holidays per year.
• Comprehensive relocation package (monetary support and legal advice) and visa sponsorship.
• Free office meals, home office setup allowance, and top-tier hardware of choice.

Hiring process

• Introductory call with Talent Acquisition.
• Technical task for submission within 5-7 days.
• Expertise interview, Stakeholder interview, and Culture interview (all conducted remotely).