Anomaly Formula: Percentage By Min

What it does:

This rule compares the latest value in your usage history with the minimum historical value. If the percentage change from the minimum meets or exceeds your defined threshold and the direction of change matches your selection, an anomaly is detected.

When to use it:

Use this formula when you want to detect increases or drops that are significantly large compared to your historical minimum. This is really helpful for finding spikes after low activity or steep decreases.

Mathematical Formula:

Let:

• L = Latest Value
• M = Minimum Value in History
• T = Threshold (as a percentage)
• %Δ = Percentage Change
• %Δ = (|L − M| / M) × 100

Anomaly Condition:

%Δ ≥ 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 → %Δ ≥ T and direction matches Change Type
☑️ Skipped → %Δ ≥ T, but direction does not match Change Type
✅ Normal → %Δ < T

Examples:

Example 1
Change Type: Increased
Threshold: 15%
History: 180, 220, 260

• If Latest Value = 200
  Result: Normal ✅
  Explanation:
    M = 180
    %Δ = (200 − 180) / 180 × 100 = 11.11%
    Percentage Change (11.11%) < Threshold (15%)

• If Latest Value = 230
  Result: Anomaly Detected ❌
  Explanation:
    M = 180
    %Δ = (230 − 180) / 180 × 100 = 27.78%
    Percentage Change (27.78%) ≥ Threshold (15%)

• If Latest Value = 150
  Result: Skipped ☑️
  Explanation:
    M = 180
    %Δ = |150 − 180| / 180 × 100 = 16.67%
    Percentage Change (16.67%) ≥ Threshold (15%)
    But direction = Decrease → does not match “Increased”

Example 2
Change Type: Decreased
Threshold: 20%
History: 300, 280, 250

• If Latest Value = 240
  Result: Normal ✅
  Explanation:
    M = 250
    %Δ = (250 − 240) / 250 × 100 = 4%
    Percentage Change (4%) < Threshold (20%)

• If Latest Value = 190
  Result: Anomaly Detected ❌
  Explanation:
    M = 250
    %Δ = (250 − 190) / 250 × 100 = 24%
    Percentage Change (24%) ≥ Threshold (20%)

• If Latest Value = 310
  Result: Skipped ☑️
  Explanation:
    M = 250
    %Δ = |310 − 250| / 250 × 100 = 24%
    Percentage Change (24%) ≥ Threshold (20%)
    But direction = Increase → does not match “Decreased”

Example 3
Change Type: Any
Threshold: 10%
History: 600, 650, 700

• If Latest Value = 640
  Result: Normal ✅
  Explanation:
    M = 600
    %Δ = (640 − 600) / 600 × 100 = 6.67%
    Percentage Change (6.67%) < Threshold (10%)

• If Latest Value = 720
  Result: Anomaly Detected ❌
  Explanation:
    M = 600
    %Δ = (720 − 600) / 600 × 100 = 20%
    Percentage Change (20%) ≥ Threshold (10%)