Rules

Anomaly Formula: Percentage-By-Max

What it does:
This rule compares the most recent usage value with the maximum value in your historical data. If the percentage difference between them meets or exceeds your defined threshold, and the direction of change matches your selected change type (Increased, Decreased, or Any), an alert is triggered.

When to use it:
Use this formula to catch sudden drops or unusual increases when compared to your highest recorded usage. It’s especially helpful for spotting irregular dips or rebounds after high usage periods.

Examples

✅ Example 1: Decrease from Max Triggers Alert

• Anomaly Formula: PercentageByMax
• Change Type: Decreased
• Threshold: 40
• History: 150, 160, 170, 180, 100
• Explanation:
  • Max = 180, latest = 100
  • Percent change = ((100 – 180) / 180) * 100 = -44.44%
  • It’s a decrease that exceeds the threshold → ✅ Alert triggered

❌ Example 2: Increase But Below Threshold

• Anomaly Formula: PercentageByMax
• Change Type: Increased
• Threshold: 25
• History: 90, 85, 80, 95, 110
• Explanation:
  • Max = 110, latest = 110
  • Percent change = ((110 – 110) / 110) * 100 = 0%
  • No meaningful increase → ❌ No alert

✅ Example 3: Sharp Change Detected (Change Type = Any)

• Anomaly Formula: PercentageByMax
• Change Type: Any
• Threshold: 50
• History: 120, 125, 130, 140, 200
• Explanation:
  • Max = 200, latest = 100
  • Percent change = ((100 – 200) / 200) * 100 = -50%
  • The change direction is “Any” and exceeds threshold → ✅ Alert triggered