Structural Diagnostic
Edge Sustainability Score (ESS)
“Will the edge still exist next quarter?”
The Edge Sustainability Score answers the forward-looking question the other diagnostics only imply: can this performance continue? It compresses the structural pipeline's stability and drift evidence into one number — high when the edge's machinery is sound beneath the results, low when current performance is being carried by conditions the structure cannot sustain.
The formula, derived
Rendered as the rounded composite sustainability read from the SDE pipeline — a single 0–1 score summarizing whether the edge's supporting structure (stability, drift, efficiency, coherence) can carry the current performance forward.
How MARS reads it
Technical explanation
Uses the SDE’s stability, drift, and z-score layers on the EV pipeline, plus branch-contribution breadth from CP3’s branch rollups.
Drift is the killer: slow EV decay hidden inside acceptable weekly readings. Rolling-window comparison across 4W/6W/12W layers exposes trajectory before the cliff.
Breadth matters because concentrated edge dies with its condition — a one-branch system is one regime change from zero.
Interpretation bands
Strong. Neutral. Weak.
Strong
Stable rolling EV, broad branch contribution, drift-resistant — the edge has structural depth.
Neutral
Durable but narrowing or drifting slowly — schedule root-cause review before decay compounds.
Weak
Concentrated, decaying, or variance-supported edge — treat current expectancy as perishable.
Use cases
Where it earns its place
- ▸Quarterly durability review: is the machine’s edge broadening or narrowing?
- ▸Early-warning on strategy decay before weekly EV turns red
- ▸Deciding whether apparent improvement justifies structural promotion from R&D
- ▸Assessing whether an edge survives session, pair, or regime concentration analysis
Edge cases
Where it can mislead
- !Healthy narrowing: deliberately specializing into a proven pocket reduces breadth by design — ESS is read against intent, not just distribution.
- !New-branch dilution: recently added branches drag breadth scores while immature; maturity-aware interpretation applies.
Example scenarios
The metric in the wild
The slow leak
Weekly EV stays green for eight straight weeks, but the 12-week rolling layer shows steady decay and Normal-branch contribution shrinking. ESS downgrades sustainability while the scoreboard still looks fine — that is the entire point.
Monte Carlo connection
Simulation assumes edge persistence across the modeled horizon. ESS is the live check on that assumption — a decaying edge makes long-horizon percentile bands progressively optimistic.
Monte Carlo Lab →Live benchmark comparison
Benchmark refresh policy keys off ESS: sustained structural change justifies re-simulation; noise does not.
7-Tier MC Benchmark →Go deeper
Operator briefs on this territory.
Deep dive — 01
Expectancy arithmetic: what a trade is worth before it happens.
The EV formula walked end to end — why per-trade worth beats realized P&L as the master metric.
Read the full brief →
Deep dive — 02
Reading the fan: Monte Carlo without self-deception.
What the percentile bands actually promise, why P10 governs sizing, and where simulation authority ends.
Read the full brief →
Deep dive — 03
MAE/MFE: what your trades did while you weren't looking.
Reading maximum adverse and favorable excursion to audit stops, targets, and exits with evidence.
Read the full brief →
ESS is calculated for you — automatically.
Every reading on this page is produced, tracked, and interpreted inside the MARS workbook ecosystem.