Pulse Documentation

name: op-overlay-delta-vs-sibling
kind: operator
category: OVERLAY
operator: OVERLAY_DELTA_VS_SIBLING
description: Per-group additive delta against a sibling group named by (Field, Value) on the SERIES host.
type: reference
applies_to: process, compose
examples_tags: [overlay, comparison, before-after]

Overlays decorate the host; no Response.Components.

Use when

Each group’s value minus one named group’s value, in the value’s own units: how far every group sits from, say, the control group.

Questions it answers:

• How much more or less revenue than the flagship store does each store bring in?
• How many points above or below the control arm is each arm’s average?

Use something else:

• OVERLAY_INDEX_VS_SIBLING when you want a ratio rather than a gap.

Params

Scope must be group. Ref.Sibling.Field (string, required) — grouper field on the host. Ref.Sibling.Value (string, required) — axis-key value identifying the sibling group. Other Ref arms → PULSE_OVERLAY_REF_INCOMPATIBLE_WITH_SHAPE.

Host shape

SERIES — grouped Process host. Subtractive twin of the sibling index. Sibling resolved via internal/processing/overlay_sibling_resolver.go.

Output

SERIES — one SeriesEntry per host group, carrying delta = group - sibling on Summary.Statistic. Sibling group itself emits 0.0 (self-vs-self). Layer Baseline = 0.

Gotchas

• Unknown (Field, Value) pair → ONE PULSE_OVERLAY_REF_UNKNOWN per layer + NaN across entries.
• Zero sibling → no warning (subtraction is defined; delta becomes the raw group value), unlike the ratio twin.
• Absent host group → SeriesEntry with unset Statistic.
• Buffered — the sibling resolver needs materialised per-group accumulators (ApplyOverlaysSeries).

See

• Skills: overlay-system, op-overlay-index-vs-sibling, op-overlay-delta-vs-margin.