Principal Data Scientist, User Ecosystem

1d•$313,000 - $365,100

About The Position

Reddit is seeking a very senior data science thought leader to shape how the company understands and improves its consumer ecosystem. The role defines measurement, modeling, and experimentation strategy for major consumer questions, including how users discover value, form habits, and deepen engagement; how Reddit understands and serves user intent; how content and communities evolve; and how systems create durable value for users, contributors, communities, and Reddit. The Principal Data Scientist will partner with leaders across Product, Engineering, Research, and Community to turn ambiguous consumer problems into scientific questions, durable analytical systems, and decisions that improve Reddit at scale. The role spans consumer science disciplines such as recommender systems, information retrieval, user modeling, personalization, lifecycle and LTV optimization, content and community modeling, knowledge graphs, causal inference, experimentation, and long-term consumer measurement. It also includes mentoring scientists and influencing the direction and health of the data science organization.

Requirements

Deep expertise in at least one relevant area, with the breadth and curiosity to work across adjacent domains.
Deep understanding of how to model and optimize systems involving users, content, communities, and feedback loops.
Ability to frame and lead ambiguous questions, identify important uncertainties, and develop a rigorous path from evidence to action.
Exceptional technical judgment across model design, objective selection, validation, experimentation, and production tradeoffs.
Advanced knowledge of modern machine-learning methods for behavioral and content data, including representation learning and sequential or contextual models.
Experience with deep-learning frameworks such as PyTorch or JAX.
Experience working across Product, Engineering, Research, and other partner teams.
Excellent written and verbal communication skills, including the ability to influence senior stakeholders and explain technical ideas clearly.
Significant experience applying data science, machine learning, statistics, experimentation, or causal inference to complex consumer products.

Responsibilities

Set scientific direction for high-impact Consumer problems spanning discovery, relevance, personalization, user growth, retention, content, and communities.
Build a durable understanding of users, their intent and needs, and behaviors that lead to lasting value.
Develop models and frameworks representing users, content, communities, and their relationships over time for use in systems operating at scale.
Determine how to measure consumer and ecosystem health when objectives compete and short-term engagement may differ from long-term value.
Set learning agendas and steer experimentation strategy to distinguish durable improvement from temporary metric movement.
Build measurement systems to evaluate heterogeneous effects across user personas, acquisition cohorts, platforms, content types, and community stages, and guide actionability in production environments.
Ensure coherence around ecosystem interactions, including feedback loops, selection effects, interference, distribution shift, content supply, and other ecosystem risks.
Translate complex technical findings into clear product and business decisions.
Develop exceptional scientists through mentoring and influence data science organization health and direction.