`official_transform_policy`

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Axis official_transform_policy on sub-layer l1_c (layer l1).

Sub-layer

l1_c

Axis metadata

Default: 'apply_official_tcode'
Sweepable: False
Status: operational

Operational status summary

Operational: 2 option(s)
Future: 0 option(s)

Options

`apply_official_tcode` – operational

Apply McCracken-Ng’s series-by-series stationarity transforms.

Each FRED-MD/QD series ships with a transformation code (t-code) 1-7 that maps to a stationarity transform: 1=level, 2=Δlevel, 5=Δlog, 6=Δ²log, etc. apply_official_tcode runs the canonical transform per series so downstream estimators see stationary inputs.

This is the canonical preprocessing path for the McCracken-Ng benchmark family. Every published replication on FRED-MD/QD uses it.

When to use

Default for FRED-MD/QD studies. Canonical replication path.

When NOT to use

Studies that want to compare alternative transform schemes (use keep_official_raw_scale and apply transforms in L2 manually).

References

macroforecast design Part 1, L1: ‘data definition is the recipe layer that pins source, target, geography, and horizon – everything downstream branches off these choices.’
McCracken & Ng (2016) ‘FRED-MD: A Monthly Database for Macroeconomic Research’, Journal of Business & Economic Statistics 34(4). (doi:10.1080/07350015.2015.1086655)

Related options: keep_official_raw_scale, official_transform_scope

Last reviewed 2026-05-04 by macroforecast author.

`keep_official_raw_scale` – operational

Skip the canonical t-codes; keep raw level data.

Series stay on their native scale (levels, ratios, indices). Useful for tree-based models that don’t need stationarity, or for studies that apply alternative transforms in L2 / L3.

When to use

Tree / forest models that don’t require stationarity; alternative-transform studies.

References

macroforecast design Part 1, L1: ‘data definition is the recipe layer that pins source, target, geography, and horizon – everything downstream branches off these choices.’

Related options: apply_official_tcode