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Sentinel · 30-day backtest

The honest calibration plot

When the Sentinel model says “5% risk,” does the real outcome actually happen ~5% of the time? Below is the answer: 898 live (predicted, observed) pairs from the last 30 days, binned into a standard reliability diagram.

Updated every 30 min · last refresh Aug 13, 2026 · CC BY 4.0 · Binned JSON · Raw outcomes

Brier score
0.292
lower is better
Calibration MAE
0.289
0 = perfect
Accuracy
43.2%
898 evaluated
F1 (binary 0.5)
0.28
P=0.20 R=0.44

Reliability diagram

Each point is one prediction bin. X axis is the mean predicted probability inside the bin; Y axis is the fraction of those forecasts where the real outcome actually happened. Perfect calibration is the diagonal line — points above the line mean the model UNDER-estimates risk; points below mean it OVER-estimates.

0.000.000.250.250.500.500.750.751.001.00perfectn=327n=46n=39n=124n=59n=68n=109n=105n=21Predicted probability (bin mean)Observed positive rate

Bubble area scales with bin count · Red = model under-estimated · Blue = model over-estimated

Per-bin breakdown

BinPredicted meanObserved rateΔn
[0.0, 0.1)0.0320.278+0.246327
[0.1, 0.2)0.1490.283+0.13346
[0.2, 0.3)0.2620.385+0.12339
[0.3, 0.4)0.3400.169-0.170124
[0.4, 0.5)0.4520.271-0.18159
[0.5, 0.6)0.5530.338-0.21568
[0.6, 0.7)0.6510.266-0.385109
[0.7, 0.8)0.7480.133-0.615105
[0.8, 0.9)0.8310.095-0.73521

Δ = observed − predicted. The 0.1 bin holds 327 of the 898 forecasts — this is where most action happens, and where the May 20 isotonic recalibration was aimed. See /sentinel/calibration for the time-series view of how this gap evolves day over day.

Per-country backtest (worst Brier first, n ≥ 5)

Countries where the forecast is currently performing worst — useful for targeting feature engineering or seeking expert review.

CountryBrierAccuracyPRnPos rate
BangladeshBD0.0000%0.00300%
BrazilBR0.0000%0.00300%
BelarusBY0.0000%0.00290%
ChinaCN0.0000%0.00300%
CubaCU0.0000%0.00300%
EgyptEG0.0000%0.281.00300%
ERER0.0000%0.00300%
EthiopiaET0.0000%0.251.00300%
IndonesiaID0.0000%0.330.06300%
IndiaIN0.0000%1.000.05300%
IranIR0.0000%0.900.38300%
North KoreaKP0.0000%0.00300%
KazakhstanKZ0.0000%0.171.00300%
LebanonLB0.0000%0.00300%
MyanmarMM0.0000%0.560.94290%
MalaysiaMY0.0000%0.360.67300%
NigeriaNG0.0000%0.00300%
NicaraguaNI0.0000%0.00300%
PhilippinesPH0.0000%0.00300%
PakistanPK0.0000%0.131.00300%

How to read these numbers

  • Brier score — mean squared error between predicted probability and actual 0/1 outcome. Lower is better. Less than 0.10 is excellent; 0.10-0.30 is OK; above 0.30 is concerning.
  • Calibration MAE — average gap between predicted-mean and observed-rate across bins. 0.00 means the model's probabilities are exactly right on average.
  • Reliability diagram — the visual version of calibration MAE. Bubble size = bin sample count.
  • F1 (P + R) — binary classification metrics at the 0.5 threshold. Useful when downstream decisions are binary (alert / no-alert).
  • The May 20, 2026 isotonic recalibration targeted the 0.1 bin specifically — see the recalibration finding.

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