Weekend Data Science Jobs in Brookline, MA (NOW HIRING)

Principal Data Scientist - Quantitative Decision Science & Advanced Analytics

Note: Fidelity will not provide immigration sponsorship for this position.

Are you interested in operating as a senior scientific leader-owningtruth, rigor, and decision qualityfor complex business problems? FidelityInstitutional'sAI Center of Excellence (AI CoE) is seeking aPrincipal Data Scientistto serve as a highly tenured individual contributor and domain authority in data science, quantitative modeling, and advanced analytics.

This role isintentionally Data Science-first,with emphasis on hypothesisdriven analysis, statistical rigor, causal reasoning, and decision science. The Principal Data Scientist is accountable forwhat the model means, whether it is correct, and whether it should be trusted-not for building or operating production systems.

The Team

The Data Science function within the Fidelity Institutional AI CoE operates as the authority on measurement, experimentation, and quantitative decisionmaking. The team comprises senior data scientists, statisticians, and quantitative researchers who partner closely with platform, product, BI, and business teams, while maintaining clear ownership of scientific rigor, evaluation frameworks, and analytical truth.

As a Principal Data Scientist, you will operate as ascientific owner and mentor,influencing methodology, standards, and strategic direction across multiple initiatives.

Key Responsibilities

Advanced Data Science & Quantitative Modeling

• Lead hypothesisdriven analyses to answer highimpact strategic and business questions

• Design, develop, and evaluate statistical, econometric, and machine learning models where appropriate

• Ensure models are theoretically sound, empirically validated, interpretable, and fitforpurpose

• Review and challenge modeling approaches for bias, stability, assumptions, and misuse

Measurement, Evaluation & Decision Science

• Define how success should be measured for complex analytics and AIenabled initiatives

• Design robust evaluation frameworks including offline validation, backtesting, and live measurement

• Ensure stakeholders can distinguish correlation from causation in analytical results

• Elevate analytics from prediction accuracyto decision quality and business impact

Experimentation & Causal Inference

• Design and review experiments including A/B tests, quasiexperiments, and observational studies

• Apply causal inference techniques (e.g., uplift modeling,DiD, matched controls) to assess incrementality

• Guide best practices for power analysis, inference, and result interpretation

• Serve as a subjectmatter expert on "What worked, why, and by how much?"

Advanced Analytics Domains

• Segmentation & Clustering:Design statistically grounded, interpretable segmentations with clear hypotheses and stability checks

• Propensity, Likelihood & Uplift Modeling:Develop probabilistic and causal models to inform prioritization and intervention strategies

• Recommendation & Prioritization Analytics:Guide recommendation logic rooted in statistics, behavioral science, and optimization-notblackboxML

• Behavioral & Journey Analytics:Analyze longitudinal behavior patterns to identify drivers, frictions, and causal levers

• Forecasting & Planning Analytics:Apply timeseries and probabilistic forecasting with uncertainty and scenario analysis

• Large Language Models & Generative AI:Design, evaluate, and implement LLM-based solutions - including RAG pipelines, classification, and extraction tasks - with rigorous benchmarking, calibration analysis, hallucination measurement, and bias auditing to ensure outputs are explainable.

Scientific Leadership & Governance (NonManagerial)

• Act as a senior reviewer and methodological authority across data science initiatives

• Set informal standards for rigor, documentation, and reproducibility

• Mentor senior and midlevel data scientists through technical guidance and peer review

Business Partnership & Influence

• Translate complex quantitative results into clear, decisionoriented narratives for senior stakeholders

• Challenge assumptions and narratives not supported by evidence

• Influence strategy by grounding discussions in data, causality, and expected impact

Expertise and Skills You Bring

Education & Experience

• Master's or PhD in Statistics, Economics, Mathematics, Operations Research, Computer Science, or related quantitative discipline

• 10-14+ years of experience in data science, quantitative research, or advanced analytics

• Proven track record of owning complex analytical problemsendtoend(from question formulation to decision impact)

Core Data Science & Scientific Expertise

• Deep expertise in statistics, probability, and experimental design

• Strong command of causal inference and incrementality measurement

• Solid grounding in forecasting, optimization, and decision science

• Demonstrated ability to assess modeling correctness, assumptions, and limitations

Technical Foundation

• Advanced proficiency in Python for analysis and modeling (NumPy, Pandas, SciPy,Statsmodels, Scikitlearn)

• Strong SQL skills and experience working with large analytical datasets (e.g.,Snowflake)

• Handson proficiency with large language models and generative AI, including prompt design, retrievalaugmented generation, structured outputs, and agentic workflows, with demonstrated rigor in designing evaluations, defining taskspecific metrics, and applying statistical testing to assess reliability, calibration, hallucination risk, and incremental value over nongenerative approaches. Equally proficient in handson code development as well as the effective use of AIpowered coding assistants, applying both to accelerate analysis while maintaining correctness, reproducibility, and scientific rigor.

Ways of Working

• Thinks like a scientist: hypothesisfirst, evidencedriven, and principled

• High bar for rigor, interpretability, and defensibility of results

• Comfortable challenging senior stakeholders using data and logic

• Values clarity, elegance, and correctness over technical novelty

• Operates as a trusted expert rather than a delivery engineer

How This Role Is Distinct

• Senior Individual Contributor:Tenured individualcontributor role with broad organizational influence

• Data Science-First:Focused on analytics, statistics, causality, and decision science

• Strategic Impact:Owns critical analytical questions that shape business decisions and investments