Rules

Anomaly Formula: Amount-By-Last

What it does:

This rule compares the most recent value in your usage history with the previous one. If the absolute difference between them meets or exceeds your defined threshold, and the type of change (increase or decrease) matches what you’ve selected, you’ll receive an alert.

When to use it:

Use this formula when you want to detect sudden jumps or drops in your spending from one period to the next—great for catching unexpected charges or immediate drops in activity.

Examples

✅ Example 1: Significant Increase Triggers Alert

• Anomaly Formula: AmountByLast
• Change Type: Increased
• Threshold: 50
• History: 120, 130, 135, 200
• Explanation:
  • The last value is 200, and the previous one is 135.
  • The difference is 200 – 135 = 65, which is above the threshold.
  • Because the change type is “Increased” and the value went up, an alert is triggered.

❌ Example 2: Decrease But Set to Increased (No Alert)

• Anomaly Formula: AmountByLast
• Change Type: Increased
• Threshold: 30
• History: 300, 250
• Explanation:
  • The last value is 250, and the previous is 300.
  • The change is -50, a decrease.
  • The condition is not met because the rule watches for increases.
  • No alert is triggered.

✅ Example 3: Sharp Drop Triggers Alert 

• Anomaly Formula: AmountByLast
• Change Type: Any
• Threshold: 40
• History: 500, 455, 420, 370
• Explanation:
  • Last value: 370, previous: 420
  • Difference: |370 – 420| = 50, which is above the threshold.
  • Change type is “Any”, so both increases and decreases qualify.
  • An alert is triggered.