Pulse Documentation

name: op-overlay-delta-vs-margin
kind: operator
category: OVERLAY
operator: OVERLAY_DELTA_VS_MARGIN
description: Per-cell additive delta against the matching axis margin (cell − margin).
type: reference
applies_to: process, compose
examples_tags: [overlay, cross-tabulation, before-after]

Overlays decorate the host; no Response.Components.

Use when

Each crosstab cell minus its row, column or grand margin, in the cell’s own units: how far a cell sits above or below its margin.

Questions it answers:

• How many points above or below the overall average rating is each segment, per question?
• Which store-by-month cells sit furthest from their store’s overall average?

Use something else:

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

Params

Scope must be cell. Ref.Margin.Axis (enum, required) — row / column / grand. Level/Within optional (default 0): nested-axis prefix truncation of the margin denominator, each in [0, axis depth) else PULSE_OVERLAY_LEVEL_OUT_OF_RANGE. Other Ref arms → PULSE_OVERLAY_REF_INCOMPATIBLE_WITH_SHAPE.

Host shape

MATRIX crosstab (Response.Crosstab.Matrix). Subtractive sibling of the margin index (ratio) and the margin z-score (standardized). Compatible with any cell aggregator.

Output

MATRIX — OverlayLayer.Payload.Matrix.Cells[r][c].Value = cell - margin. Mirrors host RowKeys / ColumnKeys / headers. Absent host cells stay absent on the overlay. Layer Baseline = 0 (delta family centerpoint).

Gotchas

• Preserves host cell’s units — a $-valued summed cell minus a $-valued row margin yields a $-valued deviation in the same currency.
• No division — never raises PULSE_OVERLAY_REF_ZERO. Unlike the margin index and the share overlays.
• Axis = grand is supported (all three axes).
• Buffered (inherent — host crosstab path always recomputes margins from raw rows).

See

• Skills: overlay-system, crosstab-guide, op-overlay-index-vs-margin.