`baseline_deviation`

Generic Description

Compares the latest value with the earlier baseline in standard-deviation units. It is documented separately because time construction, sequence ordering, window parameters, and as-of behavior materially change analytical meaning.

Simple example:

WITH [10.0, 11.0, 10.5, 16.0] AS readings
RETURN baseline_deviation(readings) AS latest_z_deviation

Consumer-Level Explanation

Use it for simple anomaly screens where the last point is the point under review. Prefer this function when the temporal assumption should be visible to the planner, especially for event streams, freshness checks, and sequence features.

More Detailed Explanation

baseline_deviation works on ordered temporal or sequence-style values inside Cypher. The practical contract is to assemble the sequence deliberately, choose the time or window parameter explicitly, and return named fields so downstream planner tooling does not invent unsupported window syntax.

Advanced Example

This example names the event stream and operational context before applying baseline_deviation, which helps planner tooling preserve the intended sequence semantics.

WITH 'sensor-1' AS subject_id,
     [{ts: 1735689600000, value: 10.0, state: 'ok'}, {ts: 1735689660000, value: 13.0, state: 'ok'}, {ts: 1735689840000, value: 9.0, state: 'warn'}, {ts: 1735690200000, value: 16.0, state: 'ok'}] AS readings
RETURN subject_id,
       baseline_deviation(readings) AS latest_z_deviation

Real Use Cases

Real Limitations And Tradeoffs