LEK Consulting (United States)

How Vitality Tracker estimates your energy expenditure: method note, version 1.0 (TDEE Engine v2)

Method note describing how Vitality Tracker estimates a person's total daily energy expenditure (TDEE Engine v2, the version in production). The estimate is the precision-weighted combination of two quantities. The first is an energy-balance measurement: the confounder-weighted m...

Vitality Tracker Sleep Scoring Methodology, Open Specification v2.0.1, public edition

Open specification of the Sleep Health Index, the sleep score used by Vitality Tracker. The index is a rolling 28-night composite of five components weighted by evidence grade and effect size: sleep regularity (35%), duration (30%), continuity (15%), circadian alignment (10%) and...