Dave Liu

Senior Data Scientist · ML Engineer · Systems Builder

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About Me

I knew I wanted to work in data before I knew what a data scientist was. At ten years old I noticed a pattern: civilizations chased gold and spices, then oil, and now—in the information age—data. It struck me that data is the modern gold, and that understanding the world at any real depth requires massive amounts of it. That idea has guided every career decision I've made since.


I believe the world is far more complex and nuanced than most people think—or care to see. Beneath every decision, every behavior, every interaction lies a web of signals that, if you look closely enough, tells a richer story than the surface ever could. To me, understanding those nuances isn't just intellectually satisfying; it's how we build a world that works better for everyone. Predicting the future starts with genuinely understanding the past and present, and I think the best version of our future begins by understanding people.


That philosophy has taken me across biotech, e-commerce, healthcare, recruiting, and fintech over the past decade. At Shipt I lead personalization for millions of grocery shoppers. Before that I helped build a cancer detection model at Freenome, designed a task-matching system that saved Change Healthcare $7M a year, and built talent-ranking models at Riviera Partners. On nights and weekends I run AutoTrader, a fully autonomous stock prediction system I built from scratch.


What ties all of that together is a belief that the hardest part of data science is rarely the model—it's getting the right data, defining the right metric, and making sure the thing actually ships. I spend as much time asking “should we be measuring this at all?” as I do writing training loops. It's an approach that's led to production systems at every company I've been part of, and one I don't plan on changing.

Experience

September 2024 – Present
Senior Data Scientist — Shipt (Personalization Team)

Lead data scientist on Shipt's Personalization team, responsible for the recommender systems behind every personalized shelf on the platform. Mentored 4 data scientists including 2 direct reports.

  • Delivered up to 23% Personalized GMV lift across multiple A/B-tested shelves (Trending Items, Similar Items, Deals For You, Complementary Items) over 90 days.
  • Designed and built a two-tower deep retrieval model to replace the legacy ALS recommender. The model improved Deals For You with 3–15% lift on Deals-specific shelves and 11% higher click-through rate overall. Offline evaluation showed +406% NDCG, +87% novelty, and +19% long-tail coverage versus the baseline—confirming the model recommends genuinely new, relevant products rather than items customers already know.
  • Designed rich user and product embeddings that go beyond surface-level text matching—capturing product descriptions, categories, pricing, retailer info, dietary preferences, and behavioral signals. Built FAISS approximate nearest neighbor infrastructure on GCS to make retrieval fast at scale.
  • Created a Personalization Interaction Score that captures the full customer funnel—views, clicks, add-to-carts, and purchases—weighted by funnel depth. This replaced single-metric optimization (e.g., GMV alone) with a composite measure that reflects how customers actually engage with shelves. The methodology has since been adopted by teammates to power next-generation real-time recommenders.
  • Developed a price-weighted ATC approach for coldstart users (new customers with no purchase history). Result: 47% engagement lift and 8% more first-time orders over 90 days. The technique was adopted across other shelves after outperforming alternatives.
  • Built an automated Shelf Attribution pipeline using fuzzy-string matching to measure Personalization's true contribution to GMV. In the process, identified that previously reported 5% attribution figures were irreproducible—actual numbers sat between 1–4%. Reported the discrepancy transparently, which helped catalyze a shift toward more defensible success metrics across the organization.
  • Designed and built a Customer Intelligence Platform (CIP) to centralize customer data, and an "Essentials" recommender shelf for commonly purchased products that serves as both a standalone shelf and a relevance filter for others.
  • Partnered with Engineering to replace brittle CSV-based recommendation delivery with Kafka-based pipelines across all legacy recommender systems—a scalable infrastructure improvement that benefits every model on the platform.
  • Designed a Retrieval-Augmented Generation (RAG) system to recommend products from Shipt's internal retailer catalogs, and built the business case that convinced stakeholders to invest in an agentic AI framework.
  • During the team's first four months, served as the sole data scientist—maintaining all 16 Discovery Science repositories, resolving issues with Search teammates, and keeping the lights on while simultaneously designing next-generation infrastructure.
November 2020 – June 2024
Machine Learning Research Engineer — Freenome

Core ML engineer at a genomics company developing a blood test for early-stage cancer detection. Worked at the intersection of infrastructure and research, building the systems that scientists depend on daily.

  • Key contributor to Freenome's core product: a multiomics cancer detection model that predicts cancer stage (1–4) from blood-draw data. Built data abstractions to handle petabyte-scale genomic datasets, unblocking cross-analyte feature development and meaningfully accelerating training and evaluation cycles.
  • Built a model comparison system that tracks research versus production model performance side-by-side—a requirement for FDA audit compliance and a tool that gave the team confidence that production models stayed aligned with research intent.
  • Designed and built large portions of Freenome's distributed ML training and serving platform, used daily by 30+ scientists and researchers. Key contributions included scaling CPU-bound training across O(100) machines, supporting multiple evaluation strategies (leave-one-out, K-fold), and building model artifact storage that made reproducibility straightforward.
  • Led the adoption of PyTorch, MLFlow, and RayTune across the ML team, replacing legacy tooling to enable GPU acceleration, experiment tracking, and hyperparameter tuning at scale.
  • Built a cloud cost monitoring system that surfaced the biggest storage and compute expenses in GCP. The visibility alone drove optimizations that saved the company over $10M annually—making it one of the highest-ROI projects I've worked on.
  • Recognized with a Servant Leadership Award, elected by managers and peers across the engineering organization.
January 2020 – November 2020
Sr. Machine Learning Engineer — Change Healthcare

Worked on ML systems for health insurance claims processing—a domain where model accuracy translates directly into operational cost savings.

  • Designed a ranking model that matches human workers to claims processing tasks based on skill, history, and task complexity. The model delivered $7M in annual value by reducing the volume of manual task assignment and the need for additional hires.
  • Built a classification model for partitioning sensitive patient documents, using image and text data to route health insurance claims to the correct processing workflow.
  • Developed internal AWS cloud tooling and production API infrastructure to support the ML team's deployment pipeline.
  • Led a cross-functional tiger team to prototype a conversational chatbot using Rasa and HuggingFace's NLP library for internal claims inquiry workflows.
January 2019 – December 2019
Data Scientist — Riviera Partners

Built ML models for an executive recruiting firm, working across the full pipeline from data collection to model serving.

  • Developed a suite of models: a classifier to estimate job-departure likelihood, a regression model to predict team sizes from resume features, and a ranking model to surface and match top candidates to open roles using a custom NDCG listwise loss function.
  • Built an end-to-end framework for rapid model prototyping, training, evaluation, and serving—enabling the team to iterate on new models without re-engineering infrastructure each time.
  • Wrote data collection scrapers to harvest structured candidate data from public sites and APIs.
January 2017 – December 2018
Undergraduate Researcher — UC Berkeley

Two concurrent research positions exploring ML applications in energy and neuroscience.

  • California Institute for Energy and Environment (CIEE): Built a recurrent neural network for predicting building energy usage, exploring how temporal patterns in consumption data can inform smarter grid management.
  • Bengson Research Lab, Sonoma State: Applied ML models to EEG data to computationally predict individualized occipital lobe activation patterns. The work showed early feasibility for brain-computer interface applications.
Earlier Roles

Where the foundation was built.

  • Data Science Intern, Castlight Health (2017) — Designed an entity matching and deduplication pipeline using gradient-boosted classifiers with hard negative mining. Achieved 85–95% precision/recall across hospital, facility, and practitioner entity types.
  • Data Science Contractor, Riviera Partners (2016) — Built a team size prediction model from public data and a Python wrapper for survival model time-series analysis. Set up Flask model-serving infrastructure.
  • URAP, Berkeley Institute of Data Science (2016) — Helped map UC Berkeley course progression through different majors by computationally organizing class taxonomies and running deduplication.
  • Data Science Intern, Doximity (2015) — Built a gradient-boosted classifier to identify malformed web-scraped articles and used reverse geocoding with fuzzy string matching to link doctor names in news articles to facility profiles.
Education
University of California, Berkeley — Class of 2018
  • BS in Computer Science and Data Science (Dual Degree)
  • Berkeley Institute of Data Science Undergraduate Research Apprenticeship (2015)

Technical Skills

Languages

Python SQL Bash Java C/C++

ML & Data

PyTorch XGBoost Scikit-learn Pandas MLFlow FAISS Gensim NLTK SpaCy

Cloud Platforms

GCP AWS Azure

Data Infrastructure

PostgreSQL Snowflake MySQL Spark Kafka

Orchestration

Airflow Flyte Metaflow GitHub Actions

Infrastructure

Docker Kubernetes Git CI/CD

What Colleagues Say

"Dave is one of the most thorough and thoughtful engineers I've worked with. He doesn't just build models—he builds the systems around them that make sure they actually work in production."

Former Colleague

Freenome

"What sets Dave apart is his willingness to ask the hard questions—about metrics, about assumptions, about whether we're solving the right problem. That intellectual honesty makes everyone around him better."

Former Manager

Shipt

"Dave taught me git, and somehow made it make sense. He has a rare ability to explain complex technical concepts in a way that doesn't make you feel stupid for not already knowing them."

Research Scientist

Freenome

Featured Project


Other Projects

Depression Classifier (2018–2022)

A personal project that grew out of curiosity about whether lifestyle patterns could predict mental health outcomes. Built an ML model trained on behavioral data (sleep, exercise, social activity, diet) that achieved a K-fold cross-validated AUC of 90% (n=110) at classifying depressive episodes. The model's feature importances were eye-opening enough to change some of my own habits—including joining a running club that I'm still part of.

Sentic Python Package (2017)

An open-source Python library for multi-dimensional sentiment analysis. Goes beyond positive/negative polarity to capture mood, attention, sensitivity, aptitude, and pleasantness across 20+ languages. Built on the SenticNet4 knowledge base. Available on PyPI.
(GitHub)

Myndful.us (2018)

An ML-powered habit-tracking web app designed to help users build healthier routines. I managed a team of 8 through design, development, and launch. The app analyzes journaling entries and activity logs to surface patterns and suggest personalized behavioral nudges.


ClimateChase (2016)

A strategy game built with Flask and React where players manage a country's energy portfolio, balancing investments across nuclear, solar, wind, and fossil fuels while responding to economic shocks and policy changes. A fun way to explore the tradeoffs in energy transition.

PDF-To-Audiobook Converter (2016)

A tool that chains together Google's Tesseract OCR engine with macOS text-to-speech to turn any PDF—including scanned documents—into listenable audio files. Built it because I wanted to "read" textbooks while running.

XRP Trade Algorithm (2014)

My first foray into algorithmic trading: a Python wrapper and terminal interface for the Ripple (XRP) API that combined real-time sentiment analysis with automated trade execution. Won 3rd place in the Ripple API Contest. The earliest sign that I'd eventually build something much bigger.

Get in Touch

Always happy to chat about data science, ML systems, or interesting problems.

7david12liu@gmail.com

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