V-Lab
S&P GSCI Coffee Index Zero Slope Spline-GARCH Volatility Analysis
Volatility prediction for Monday, September 14th, 2026
1 Day
35.63%
decreased by 1.01%
1 Week
35.60%
decreased by 1.04%
1 Month
35.51%
decreased by 1.13%
Analysis last updated: Saturday, September 12, 2026 at 12:56 AM UTC
News Impact Curve
How returns affect tomorrow's volatilityVolatility Forecast
How volatility evolves over timeParameter Estimates
Jan 2, 1990 to Sep 11, 2026Model Insight
This model fits a time-varying baseline (a spline), so volatility mean-reverts toward a slowly-shifting long-run level rather than a constant. Short-run deviations decay with a half-life of 22 trading days.
τ
Zero Slope Spline-GARCH Model
Tap to view equation
Time-varying baseline: volatility reverts to a slowly-shifting spline trend
| Param | Value | t-stat |
|---|---|---|
| ωconst | 0.6559 | 9.86*** |
| αARCH | 0.0602 | 6.81*** |
| βGARCH | 0.9084 | 63.97*** |
Spline Coefficients
K=3
| γ1 | -0.0124 | -5.06*** |
| γ2 | 0.0169 | 4.82*** |
| γ3 | -0.0055 | -3.27*** |
0.969
Persistence22d
Half-lifeτ
Zero Slope Spline-GARCH Model
Tap to view equation
| Parameter | Value | t-statistic |
|---|---|---|
ω const Unconditional variance weight | 0.6559 | 9.86*** |
α ARCH Response to squared shocks | 0.0602 | 6.81*** |
β GARCH Volatility persistence | 0.9084 | 63.97*** |
Spline Coefficients
K=3
| γ1 | -0.0124 | -5.06*** |
| γ2 | 0.0169 | 4.82*** |
| γ3 | -0.0055 | -3.27*** |
Persistence:
0.969
Half-life:
22 days
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