SETPOINTk.ai · Metric Surface
SPI — SETPOINT Index
SPI is a longitudinal signal describing regulation stability, recovery behavior, and adaptive variability across time.
Think of SPI as a “motion trace” of regulation: stability regimes, recovery slopes, and variability structure across a window of time.
Stability regime
Not “flatness.” A coherent baseline pattern that persists across time.
Recovery slope
After a stressor, how consistently the system returns toward baseline.
Structured variability
Flexibility with structure. Variability that remains organized, not chaotic.
What SPI Represents
SPI is not a snapshot measurement. It models how physiology behaves across time — emphasizing recovery dynamics, fluctuation structure, and regulation coherence.
Conceptual Analogy
If traditional metrics resemble a single photograph, SPI resembles a motion trace — capturing direction, stability, and response patterns rather than isolated values.
Interpretation Boundary
SPI is descriptive, not diagnostic. It supports observation and pattern recognition but does not replace clinical judgment or guideline-based evaluation.
Prefer trends over points
SPI is designed for sequences. Single-day values are less meaningful than direction and persistence.
Look for regime shifts
The key signal is a stable change in behavior across multiple measurements—not normal day-to-day noise.
Context matters
Travel, illness, sleep disruption, training load, menstrual cycle, and medication changes can alter trajectories.
Using SPI as a diagnosis
SPI does not classify disease or replace clinical evaluation. It is an interpretive descriptor of longitudinal behavior.
Cross-person comparisons
Comparing SPI between individuals without baseline context can be misleading. Within-person change is typically the primary lens.
“Higher is always better”
Interpretation is not monotonic. Some contexts demand flexibility; others demand stability. Meaning depends on the pattern and context.
Sequence, not a single reading
SPI is most meaningful when computed from a run of measurements. It is designed to describe behavior across time, not a one-off snapshot.
Consistency over perfection
Irregular sampling and occasional missing data can be tolerated, but consistent collection improves interpretability and reduces false “regime shifts.”
Noise-aware by design
Wearables and home measurements contain noise. SPI is intended to summarize structure (stability/recovery/variability), not overreact to single outliers.