ATRN transforms the absolute ATR into a relative measure by normalizing it to a [0,1] scale using min-max scaling over a lookback window. This answers the question: "Is current volatility high or low *compared to recent history*?"
While ATR tells you *how much* an asset moves, ATRN tells you *how unusual* that movement is relative to the asset's own recent behavior. A value near 1 means volatility is at its recent high; a value near 0 means volatility is at its recent low; 0.5 means volatility is average.
ATRN is a practical extension of Wilder's ATR, developed to solve the **context problem** in volatility analysis. Raw ATR values are meaningless in isolation—you need to compare them to something. Some traders compare ATR to price (NATR), which gives a percentage. ATRN takes a different approach: it compares ATR to its own recent range.
This normalization approach is common in machine learning and signal processing, where inputs are scaled to [0,1] for better model performance. ATRN applies the same principle to volatility measurement.
## Architecture & Physics
ATRN is built on three components:
1.**True Range (TR)**: Captures the full range of price movement including gaps.
2.**RMA Smoothing**: Wilder's exponential average ($\alpha = 1/N$) to smooth TR into ATR.
3.**Min-Max Normalization**: Scales ATR to [0,1] over a lookback window.
### The Lookback Window
The lookback window is set to $10 \times period$. For the default period of 14:
- Lookback = 140 bars
- This captures roughly 6-7 months of daily data
- Provides stable min/max anchors while remaining responsive to regime changes
### Edge Case: Constant Volatility
When max ATR equals min ATR (perfectly constant volatility), the denominator becomes zero. ATRN returns 0.5 in this case—the midpoint—indicating "average" volatility by default.
| **0.0 - 0.2** | Volatility at recent low | Extreme quiet; mean reversion likely |
## Common Pitfalls
* **Scale Independence**: ATRN is relative to the asset's own history. An ATRN of 0.8 on AAPL is not comparable to 0.8 on BTC—they're measuring different things.
* **Lookback Sensitivity**: The 10×period lookback window defines "recent history." Shorter lookbacks react faster but may produce whipsaw signals. The default balances responsiveness and stability.
* **Lag**: Like all smoothed indicators, ATRN lags the actual volatility state. By the time ATRN hits 1.0, the volatility spike may already be fading.
* **Not a Directional Indicator**: ATRN measures the magnitude of volatility, not its direction. High ATRN can occur in both rallies and crashes.
## Use Cases
1.**Position Sizing**: Scale position size inversely with ATRN—smaller positions when ATRN is high, larger when low.
2.**Stop Loss Adaptation**: Tighter stops when ATRN is low (quiet market), wider stops when ATRN is high (volatile market).
3.**Regime Detection**: Use ATRN thresholds to switch between mean-reversion (low ATRN) and trend-following (high ATRN) strategies.
