field notes
Insights
War stories from production data work. What broke, what we measured, and what we'd tell you over coffee before you build it yourself.
data quality · analytics · call centers2026-08-10
How a Bad Join Created a 5x Reporting Error
A call center believed carriers were rejecting 61 percent of its calls. The real number was 11 to 12. The difference was one join that silently dropped 81 percent of rows.
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machine learning · causal measurement · e-commerce2026-08-09
Measuring Marketing Lift With a Permanent Control Group
Retention tools claim credit for revenue that would have arrived anyway. The fix is old-fashioned science: a permanent randomized holdout that is never emailed.
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llm · nlp · hospitality2026-08-08
What It Takes to Label 67,962 Reviews With an LLM
Sentence-level labeling across an 84-aspect ontology, 26 ontology versions, and a model bake-off that kept 95 percent of quality at a quarter of the cost.
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