@@ -130,10 +130,11 @@ The model uses **three effective free parameters**:
130130| Parameter | Value | Description |
131131| ---------| ------| ------------|
132132| $\sigma_0$ | 0.25 | Long-run annual volatility scale |
133- | $\kappa$ | 0.02 | Mean-reversion speed of precision |
133+ | $\kappa$ | 0.5 | Mean-reversion speed of precision |
134134| $c$ | 10.0 | Shock intensity scaling |
135135
136- These parameters control the scale and persistence of shock activity and were ** not tuned** to fit the q-variance parabola.
136+ Note: In the latest code version,
137+ 𝜅 is set in a ** fast-mixing regime** to improve stability and reduce sensitivity to simulation length.
137138
138139---
139140
@@ -146,22 +147,31 @@ All remaining parameters are fixed *a priori* for numerical stability and scale
146147| ` a_shape ` | 1.5 | Diffusion discretisation constant |
147148| ` lam_cap ` | 500.0 | Poisson intensity cap (numerical safeguard) |
148149| ` dt ` | 1 / 252 | Trading-day discretisation |
149- | ` seed ` | 3 | Reproducibility only |
150+ | ` burn_in ` | 2000 | burn-in removed from output |
151+ | ` seed ` | 6 | Reproducibility only |
150152| ` s0 ` | 100.0 | Initial price |
151- | ` n_days ` | 120,000 | Simulation length |
152153
153154The Poisson cap is set sufficiently high that it is ** rarely binding** and does not affect the fitted q-variance curve.
154155
155156---
156157
157158## Results
158159
160+ ex: n_days = 100K
159161<p align =" center " >
160- <img src =" result1 .png" width =" 650 " >
162+ <img src =" Results_n_days_100K .png" width =" 650 " >
161163</p >
162164
163- Simulated price paths reproduce the q-variance relationship with a global
164- goodness-of-fit of ** R² ≈ 0.996** , exceeding the challenge threshold of ** 0.995** .
165+ | Simulation Length (n_days) | σ₀ (fitted) | z₀ (fitted) | R² |
166+ | -------------------------: | ----------: | ----------: | ----: |
167+ | 5,000 | 0.346 | 0.048 | 0.947 |
168+ | 10,000 | 0.344 | 0.054 | 0.970 |
169+ | 15,000 | 0.315 | 0.055 | 0.972 |
170+ | 60,000 | 0.318 | 0.002 | 0.991 |
171+ | 100,000 | 0.323 | −0.012 | 0.997 |
172+ | 120,000 | 0.318 | −0.017 | 0.997 |
173+ | 180,000 | 0.297 | −0.012 | 0.990 |
174+
165175
166176## Dataset Notes
167177
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