Senior Experimentation Scientist

At Preply, we are unlocking human potential through learning.

We believe learning with a great tutor is life-changing. That’s why we match online tutors from across the globe with learners and empower them to create live language classes with AI-powered tools and learning materials. This is how we deliver progress, create engagement and keep our global community of learners motivated. So far, over 32,000 tutors have given more than 15 million lessons to learners from over 175 countries.

Meet the team!

We A/B test most of our changes on production, both product and technical, before scaling it to all customers. The Experimentation Squad owns the whole infrastructure and the framework that are used to make those business-vital decisions.

We define the framework, including the overall evaluation criteria, set of target metrics, and available test types: student-sided, tutor-sided, clustered; frequentist, bayesian, interleaving; superiority, non-inferiority. We analyze performance of the experimentation program using multiple holdout groups and push product management in the right direction. Finally, we’re in charge of improving the company’s experimentation culture and education, and keeping institutional memory.

We have diverse technical challenges (sometimes we write about them on our Engineering Blog) that will allow you to develop your skills across the stack. Visit our Tech Radar to learn more about the technologies we use at Preply!

What you’ll be doing:

• Unlock the potential of product and marketing teams by researching and implementing new approaches for hypothesis testing (clustering, interleaving, geolift,..);
• Identifying and designing value-adding insights solutions, leveraging data to optimize our strategy;
• Establish credibility and quality of the experimentation framework;
• Quantify the impact of product and marketing development and distinct initiatives in order to identify growth opportunities and help top management in prioritizing Preply’s roadmap;
• Level up the experimentation culture across the company;
• Support engineers to build and maintain high-quality data pipelines;
• Collaborate with product teams to help them tackle technical issues with A/B testing;
• Collaborate with marketing teams to measure the impact of changes in budget relocation.

What you need to succeed:

• Extensive experience in the data science & analytics field (5+ years’ experience at least);
• Experience in product or marketing experimentation and desire to dive deeper into the sphere and research best industry practices to build state-of-the-art experimentation in Preply;
• Strong curiosity, problem-solving, and problem-finding skills;
• Solid SQL hands-on experience, and strong knowledge of Python (NumPy, Pandas, SciPy);
• Good understanding of statistical analysis concepts such as p-value, null hypothesis, and confidence interval;
• Eagerness to take responsibility for systems that directly impact the company's decision-making process;
• Passion for analyzing data to inform decisions, measuring and monitoring;
• Willingness to educate colleagues (doing knowledge-sharing sessions);
• Excellent written and verbal communication skills. Fluent English is a must.

Nice to have:

• Experience applying advanced experimentation - bayesian testing, causal impact analysis;
• Knowledge of Airflow, Redshift (or any other Data Warehouse DBs - Snowflake, BigQuery..);
• Knowledge of Looker, Amplitude, Databricks, or other BI tools.

Why you’ll love it at Preply:

• An open, collaborative, dynamic and diverse culture;
• A generous monthly allowance for lessons on Preply.com, Learning & Development budget and time off for your self-development;
• A competitive financial package with equity, leave allowance and health insurance;
• Not in Barcelona? We offer an attractive relocation package to join us in our Preply Barcelona Hub;
• Access to free mental health support platforms;
• Access to Gympass-partnered wellness and gym centers throughout Spain to promote and support well-being and physical health; 
• The opportunity to unlock the potential of learners and tutors through language learning and teaching in 175 countries (and counting!).

Our Principles

• Care to change the world - We are passionate about our work and care deeply about its impact to be life changing.
• We do it for learners - For both Preply and tutors, learners are why we do what we do. Every day we focus on empowering tutors to deliver an exceptional learning experience.
• Keep perfecting - To create an outstanding customer experience, we focus on simplicity, smoothness, and enjoyment, continually perfecting it as every detail matters.
• Now is the time - In a fast-paced world, it matters how quickly we act. Now is the time to make great things happen.
• Disciplined execution - What makes us disciplined is the excellence in our execution. We set clear goals, focus on what matters, and utilize our resources efficiently.
• Dive deep - We leverage business acumen and curiosity to investigate disparities between numbers and stories, unlocking meaningful insights to guide our decisions.
• Growth mindset - We proactively seek growth opportunities and believe today's best performance becomes tomorrow's starting point. We humbly embrace feedback and learn from setbacks.
• Raise the bar - We raise our performance standards continuously, alongside each new hire and promotion. We build diverse and high-performing teams that can make a real difference.
• Challenge, disagree and commit - We value open and candid communication, even when we don’t fully agree. We speak our minds, challenge when necessary, and fully commit to decisions once made.
• One Preply - We prioritize collaboration, inclusion, and the success of our team over personal ambitions. Together, we support and celebrate each other's progress.

Diversity, Equity, and Inclusion

Preply is committed to creating a diverse and inclusive environment where people from all backgrounds can thrive. Different opinions and viewpoints are key ingredients in our success as a multicultural Ed-Tech company.

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