Compression, Recovery, and Reserve Operationalizing Population Allostatic Load

ATI-PALI-01 defined Population Allostatic Load (PAL) as the accumulated adaptive burden a population carries when compression outpaces recovery. This paper specifies how to measure it. The Population Allostatic Load Index (PALI) is built from four quantities: compression, the recovery rate that expresses Collective Recovery Potential, reserve, and an amplification term. Burden is accumulated through time using the leaky-accumulator rule shared with HACT, then adjusted for reserve. Every variable is assigned to exactly one role in a published registry, and validation targets are never used as inputs. Indicators are standardized against a fixed reference period so that long-run trends remain visible. The paper is a measurement architecture, not a causal claim, and it is designed to be testable, refinable, and falsifiable.