Apple Services Engineering (ASE) powers AI and LLM features across App Store, Music, Video, and more. As these systems increasingly rely on LLM Judges and automated evaluators to score model performance at scale, the trustworthiness of those evaluation signals becomes mission-critical. We believe that to build exceptional LLMs, you need exceptional mechanisms to validate the signals used to train and evaluate them.
Description
As a Principal Applied Scientist on the Human Centered AI team, you will be the technical engine behind our Data Quality Validation framework. This is a high-impact individual contributor role for a scientist who wants to architect and build — not just advise. You will own the data science methodology underpinning our data quality validation models, design the statistical frameworks that govern judge reliability, and work hands-on to close the loop between automated evaluation and human ground truth.
You will be the person who answers the hardest question in our stack: "Can we trust the evaluators that are evaluating our models?"
Responsibilities
Design, develop, and iterate on the reasoning agent that serves as our adjudicator, auditing Production LLM Judge outputs for hallucination, drift, and systematic bias Develop the statistical and ML approaches that detect when Production LLM Judges diverge from ground truth, including confidence calibration, entropy-based uncertainty quantification, and out-of-distribution detection Define the algorithms that determine what gets routed for deeper review, moving the team from random sampling to principled, risk-stratified smart sampling Design the hierarchical weighting model and the confidence interval framework that replaces misleading point estimates with statistically rigorous ranges Establish the standards for how immutable ground truth sets are built, versioned, and validated, including inter-annotator agreement protocols Partner with Autograder Developers to validate new LLM Judge through our standard validation processes, ensuring LLM Judges are rigorously validated before reaching production Serve as the scientific authority on data quality evaluation methodology for partner teams across ASE, translating complex statistical findings into clear decision-readiness signals for engineering and leadership stakeholders
Minimum Qualifications
Master's degree in Statistics, Data Science, Machine Learning, Computer Science, or a related quantitative field 8+ years of hands-on experience in applied data science, ML research, or evaluation science Deep expertise in uncertainty quantification and model calibration — including entropy modeling and Bayesian approaches Demonstrated experience building disagreement detection or anomaly detection models in production ML systems Strong command of statistical measurement frameworks — inter-rater reliability, correlation analysis, and statistical process control Proven experience designing or contributing to Human-in-the-Loop (HITL) or active learning pipelines Proficiency in Python for statistical modeling, ML experimentation, and data pipeline development Exceptional ability to translate rigorous statistical methodology into clear, actionable guidance for engineering and product partners
Preferred Qualifications
PhD in Statistics, Computer Science, Machine Learning, or a related field Experience specifically in LLM evaluation science — including autograder validation, judge-as-a-model frameworks, or RLHF data quality Hands-on experience with large-scale reasoning models (e.g., 70B+ parameter models) used in chain-of-thought evaluation or meta-reasoning contexts Experience defining governance gates or certification pipelines for AI systems in a CI/CD context Familiarity with out-of-distribution detection techniques for identifying input drift in live production systems Track record of publishing or presenting evaluation methodology work internally or externally
At Apple, base pay is one part of our total compensation package and is determined within a range. This provides the opportunity to progress as you grow and develop within a role. The base pay range for this role is between $201,300 and $302,200, and your base pay will depend on your skills, qualifications, experience, and location.
Apple employees also have the opportunity to become an Apple shareholder through participation in Apple’s discretionary employee stock programs. Apple employees are eligible for discretionary restricted stock unit awards, and can purchase Apple stock at a discount if voluntarily participating in Apple’s Employee Stock Purchase Plan. You’ll also receive benefits including: Comprehensive medical and dental coverage, retirement benefits, a range of discounted products and free services, and for formal education related to advancing your career at Apple, reimbursement for certain educational expenses — including tuition. Additionally, this role might be eligible for discretionary bonuses or commission payments as well as relocation. Learn more about Apple Benefits
Note: Apple benefit, compensation and employee stock programs are subject to eligibility requirements and other terms of the applicable plan or program.
Apple is an equal opportunity employer that is committed to inclusion and diversity. We seek to promote equal opportunity for all applicants without regard to race, color, religion, sex, sexual orientation, gender identity, national origin, disability, Veteran status, or other legally protected characteristics. Learn more about your EEO rights as an applicant
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Apple accepts applications to this posting on an ongoing basis.