# Filter 7: Seasonality index

**Status:** Not started.

**Data key:** `seasonalityIndex`. Calculation:
[filter-calculations.md](../filter-calculations.md) §7.

## Findings

No filter-specific findings yet.

Cross-filter findings that affect this filter, in
[00-cross-filter.md](00-cross-filter.md): 2 and 11 (county aggregation),
12 (Alaska and Hawaii not covered), and 15 (source text cites the station
Normals).

## Decisions

None yet.

## Tasks

Not started; follow the per-filter review checklist in
[pipeline-plan.md](../pipeline-plan.md) §5.