D08-F07-A07 · LEVEL 2 GUIDED LAB · SYNTHETIC DATA

Range Expansion Index

Does range-qualified directional change favor expansion up or down? Walk the evidence clock one stage at a time. This lab teaches the publication contract; it does not simulate returns, platform parity, or trade performance.

Selected expression

package convention: REI=100*sum gated directional change/sum absolute gated change

Availability rule

A state at t may use only observations available through t; confirmed swings retain their confirmation timestamp and are never relabeled as known at the pivot bar.

calculated · step 1 of 7

Verified synthetic fixture

This lab is paired with datasets/implementation-fixtures.json: 96 deterministic, oldest-to-newest observations spanning oscillating, rising, and moderating regimes. It is teaching data—not market history or predictive evidence.

Canonical latest output (D08-F07-A07)
{
  "value": -8.09257352049753
}

Executable checks cover this result, flat/zero-volume boundaries, invalid timestamps, and prefix causality in both language entry points.