Rules

Anomaly Formula: Percentage-By-Min

What it does:
This rule compares the most recent usage value with the minimum 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 when you want to detect whether your current usage is unusually high or low compared to the lowest value in your usage history. This is helpful for spotting unexpected surges or for benchmarking against the lowest baseline.

Examples

✅ Example 1: Increase from Min Triggers Alert

• Anomaly Formula: PercentageByMin
• Change Type: Increased
• Threshold: 60
• History: 80, 78, 75, 90, 130
• Explanation:
  • Minimum = 75, latest = 130
  • Percent change = ((130 – 75) / 75) * 100 = 73.33%
  • It’s an increase above the threshold → ✅ Alert triggered

❌ Example 2: Decrease but Below Threshold

• Anomaly Formula: PercentageByMin
• Change Type: Decreased
• Threshold: 40
• History: 100, 97, 95, 92, 85
• Explanation:
  • Minimum = 85, latest = 85
  • Percent change = ((85 – 85) / 85) * 100 = 0%
  • No significant decrease → ❌ No alert

✅ Example 3: Significant Change in Either Direction (Change Type = Any)

• Anomaly Formula: PercentageByMin
• Change Type: Any
• Threshold: 50
• History: 300, 280, 270, 260, 120
• Explanation:
  • Minimum = 120, latest = 120
  • Percent change = ((120 – 260) / 120) * 100 = -116.67% (calculated from min = 120 and latest = 260 would be invalid; reversed numbers)
  • Let’s correct this:
    • Minimum = 120, latest = 260
    • Percent change = ((260 – 120) / 120) * 100 = 116.67%
  • Change type is “Any”, and it’s well above the threshold → ✅ Alert triggered