Metric Check Comparisons¶
The comparison decides what a Metric check measures and what Min and Max bound. There are three: Absolute Value bounds the field's value itself, while Absolute Change and Percentage Change bound how much it moved since the previous measurement.
Different from the Volumetric check comparisons
The Volumetric check uses the same three comparison names, but its behavior is entirely different. A Volumetric check measures the container's row count and compares it with the daily counts of earlier calendar days. A Metric check measures one field's value on a single row and compares it with the measurement of the previous Scan of the same read strategy. Do not carry limits or expectations from one check to the other.
Absolute Value¶
Absolute Value asks: is the value inside [Min, Max]?
- What is compared. The field's value on the one row the Scan evaluates.
- What Min and Max mean. Values of the field, in its own unit.
- Anomaly rule. A value below Min or above Max raises an anomaly. Both limits are inclusive.
- History. None. Every Scan is compared directly, including the first.
- Best for. A KPI with a known acceptable range, such as a rate between 2% and 8%.
Example. Min 0.02, Max 0.08:
| Scan | Value |
|---|---|
| Monday | 0.051 |
| Tuesday | 0.012 |
| Wednesday | 0.047 |
Absolute Change¶
Absolute Change asks: did the value move by more than expected since the previous Scan?
- What is compared. The value against the most recent measurement from an earlier Scan of the same read strategy (Incremental or Full).
- What Min and Max mean. Movements, in the field's unit. A negative Min allows the value to fall by up to that amount, and a positive Min requires it to grow by at least that amount.
- Anomaly rule. If the value is below the previous measurement plus Min, or above the previous measurement plus Max, an anomaly is raised. Both limits are inclusive.
- History. The first Scan of each read strategy only records the value.
- Best for. A value that drifts over time but should not jump between Scans, such as a running balance.
Example. Min 30, Max 70:
| Scan | Previous measurement | Value | Change |
|---|---|---|---|
| #1 | - | 100 | - |
| #2 | 100 | 150 | 50 |
| #3 | 150 | 220 | 70 |
| #4 | 220 | 300 | 80 |
Percentage Change¶
Percentage Change asks: did the value move by more than a given percentage since the previous Scan?
- What is compared. The same pair as Absolute Change: the value against the most recent measurement of the same read strategy.
- What Min and Max mean. Percentages of the previous measurement. The form labels them Min Percentage and Max Percentage and takes values in percent (enter
-20for a 20% decrease). Through the API they are decimals (-0.2). - Anomaly rule. If the change, as a percentage of the previous measurement, falls below Min or above Max, an anomaly is raised. Both limits are inclusive.
- History. The first Scan of each read strategy only records the value.
- Best for. A total whose scale varies, where a fixed amount would be too strict on a big day and too loose on a small one.
Example. Min -20, Max 50:
| Scan | Previous measurement | Value | Change |
|---|---|---|---|
| #1 | - | 100 | - |
| #2 | 100 | 150 | 50% |
| #3 | 150 | 120 | -20% |
| #4 | 120 | 65 | -45.83% |
After Scan #4, the anomalous value becomes the previous measurement: Scan #5 is compared with 65, not with 120.
Choosing a Comparison¶
| The expectation you want to enforce | Comparison |
|---|---|
| The value always stays between X and Y | Absolute Value |
| The value never moves by more than a fixed amount between Scans | Absolute Change |
| The value never moves by more than a percentage between Scans | Percentage Change |
The comparison is chosen when the check is created and is locked after the first Scan that includes the check. See How It Works.
See Also¶
-
Anomaly Reporting
What the Record Anomaly reports, how to read its numbers, and what the source record shows.
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Examples
Three production scenarios: a daily revenue total, a rate for one region, and a running balance.
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Best Practices
Guidelines for putting the value in one row, choosing the read strategy and comparison, and reading change anomalies.
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Permissions
The team permission each action needs: view, create, edit, validate, archive, restore, and delete.
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How It Works
The complete reference: definition, why the check needs exactly one row, the properties, the previous measurement, and the locks after the first Scan.