Residual geometry
When residuals reveal the truth
Volatility models can make a series look well-behaved,
but residuals often tell a different story.
SNAP2D measures how much structure survives after a linear
baseline and a GARCH volatility model, and pushes residual
autocorrelation close to white-noise levels — without
touching your forecasting stack.
The chart shows residual ACF for the
same instrument under three treatments:
-
Baseline AR(2) — slow decay,
strong positive autocorrelation.
-
GARCH(1,1) — improved volatility modelling,
but residual structure remains.
-
SNAP2D — residuals collapse towards zero
lag after lag.
For quant teams, it draws the line between modelling
volatility and certifying that the residual no longer
carries exploitable structure.
R_fin — residual gain factor
SNAP2D’s proprietary residual gain metric
R_fin summarises this improvement as a
single structural efficiency score against AR and GARCH
baselines.
Values around 1 indicate noise-dominated regimes;
values above 1 indicate nonlinear structure, and values
significantly above 1.5 mark strong structural coherence.
Alongside R_fin, SNAP2D also computes
R_fin_IQR, a robustness variant that looks
only at the central 50% of residuals.
High R_fin_IQR means the structural gain is
not just driven by tail events, but by the core of the
distribution.
PASS / FAIL — certification readout
SNAP2D can optionally run a
multi-scale certification step.
When the residual geometry remains coherent across the
tested scales, the run is marked PASS
together with a minimum margin z_min and the
list of scales.
Certification is currently calibrated for
weekly horizons, where invariance is
statistically meaningful.