Doug Turnbull

Co-founder of OpenSource Connections (OSC); co-author of Relevant Search (O’Reilly). Search relevance consultant and practitioner; author of the Softwaredoug blog.

Known For

• Relevant Search book (with John Berryman)
• Bayesian BM25 (BB25) — calibrated BM25 probabilities for principled hybrid fusion
• Practical Elasticsearch relevance tuning
• “What is Relevant?” — task-centered definition of relevance

Articles

• What is Presentation Bias in Search

• What AI Engineers Should Know about Search

• Bayesian BM25 is Cool

• What is a Relevant Search Result

• Practical BM25 - The Effect of k1 and b

• Semantic Search Without Embeddings

• Finding the Relevance Cutoff - When to Stop Showing Search Results

• Getting Started on Search Relevance for the Understaffed Search Team

Affiliations

• Shopify (current)

Key Concepts

• BM25
• Hybrid Search
• Learning to Rank
• Search Evaluation
• Judgment Lists

Affiliations

• OpenSource Connections (OSC) — same org as Max Irwin
• Can BM25 be a Probability — BB25 framework; calibrating BM25 as probability for principled hybrid fusion
• Metadata - The 3rd Kind of Retrieval — attribute-based retrieval as a third paradigm beyond lexical + embeddings
• Classic ML to Cope with Dumb LLM Judges — combining many dumb LLM judges via decision tree to improve precision