Anomaly Formula: Amount By Max

What it does:
This rule compares your latest usage with the highest value from your previous usage history (excluding the latest value). If the change exceeds your defined threshold—and matches the direction you’re watching (increase, decrease, or any)—it’s flagged as an anomaly.

When to use it:
Use this formula when you want to know if your current usage surpasses or drops sharply below your previous maximum. Ideal for monitoring cost spikes beyond known limits.

Mathematical Formula:

Let:

• L = Latest Value
• M = Max of previous values
• T = Threshold
• D = |L − M| (absolute difference)

Anomaly Condition:

D = |L − M| ≥ T

Direction Validation (based on Change Type):

• If Change Type = Increased, condition is valid only if L > M
• If Change Type = Decreased, condition is valid only if L < M
• If Change Type = Any, direction check is not required

Outcomes:

❌ Anomaly Detected → D ≥ T and direction matches Change Type
☑️ Skipped → D ≥ T, but direction does not match Change Type
✅ Normal → D < T

Examples:

Example 1

Change Type: Increased
Threshold: 40
History: 200, 220, 240

• If Latest Value = 260
  Result: Normal ✅ 
  Explanation:
    Max: 240
    Change: 260 − 240 = 20
    Absolute Difference (20) < Threshold (40)

• If Latest Value = 300
  Result: Anomaly Detected ❌ 
  Explanation:
    Max: 240
    Change: 300 − 240 = 60
    Absolute Difference (60) ≥ Threshold (40)

• If Latest Value = 100
  Result: Skipped ☑️ 
  Explanation:
    Max: 240
    Change: 100 − 240 = −140
    Absolute Difference (140) ≥ Threshold (40)
    But direction = Decrease → does not match “Increased”

Example 2
Change Type: Decreased
Threshold: 30
History: 400, 420, 410

• If Latest Value = 395
  Result: Normal ✅
  Explanation:
    Max: 420
    Change: 395 − 420 = −25
    Absolute Difference (25) < Threshold (30)

• If Latest Value = 360
  Result: Anomaly Detected ❌
  Explanation:
    Max: 420
    Change: 360 − 420 = −60
    Absolute Difference (60) ≥ Threshold (30)

• If Latest Value = 460
  Result: Skipped ☑️
  Explanation:
    Max: 420
    Change: 460 − 420 = 40
    Absolute Difference (40) ≥ Threshold (30)
    But direction = Increase → does not match “Decreased”

Example 3
Change Type: Any
Threshold: 50
History: 100, 110, 120

• If Latest Value = 130
  Result: Normal ✅
  Explanation:
    Max: 120
    Change: 130 − 120 = 10
    Absolute Difference (10) < Threshold (50)

• If Latest Value = 200
  Result: Anomaly Detected ❌
  Explanation:
    Max: 120
  Change: 200 − 120 = 80
  Absolute Difference (80) ≥ Threshold (50)