---
license: cc-by-nc-sa-4.0
language:
- en
tags:
- gemma
- quantization
- qat
- benchmark
- reproducibility
- llm-governance
- routing
pretty_name: Gemma 4 Quantization-Regime Study (QAT Q4_0 vs PTQ Q4_K_M)
size_categories:
- n<1K
---

# Gemma 4 Quantization-Regime Study (QAT Q4_0 vs PTQ Q4_K_M)

A same-day 2×2 study (quantization regime × released model pair) of
governed routing quality for Gemma 4 12B IT (dense; a clean same-base
pair) and a 26B-class MoE released pair on one RTX 5070 Ti, run under a
fixed, bit-identical governance stack via Ollama.
Companion/sequel to the *Gemma 4 MTP Quality–Throughput Study* (2026-08-09,
DOI 10.5281/zenodo.21860461).

Author: Taiko Toeda, Independent Researcher
ORCID: https://orcid.org/0009-0001-7267-0201
Version: 1.0.2
DOI: [10.5281/zenodo.21903706](https://doi.org/10.5281/zenodo.21903706) (v1.0.2; concept DOI [10.5281/zenodo.21875512](https://doi.org/10.5281/zenodo.21875512) resolves to the latest)

## Result boundary

Aggregate route correctness spanned 0.738–0.760 on Core-500 (N=500 rows =
100 paraphrase stems × 5); no equivalence test was run, and one
cross-model contrast (12B-PTQ vs 26B-PTQ) is nominally significant
(p=0.035). The within-pair regime effects were individually marginal and
oppositely signed — QAT −0.012 on the dense 12B (McNemar p=0.070) and
+0.018 on the 26B released pair (p=0.078) — and the regime × pair
interaction, an exploratory single-run endpoint, was +0.030 with a
stem-clustered bootstrap 95% CI of [+0.010, +0.052] (task-iid CI
[+0.008, +0.052]), concentrated in the volatile-current task family
(crossed pattern). Cross-regime byte-identity of temperature-0 outputs
was only 23–32 %, against same-configuration Smoke-100 repeats of
100/100 in all four cells (including the CPU-offloaded 26B-PTQ cell,
across run windows) and a 100/100 `num_ctx` byte-identity control.
Safety-critical failure rates were 0.000 in seven of eight runs, with a
single over-verification event (0.008) in 26B-PTQ Core-500.

These results apply only to the measured GPU, runtime (Ollama 0.30.6),
the released model artifacts named in `ENVIRONMENT.md`, one governance
stack, and routing/abstention-style tasks. The 26B released pair
confounds regime with a possible base revision (25.8B vs 25.2B), an
expert configuration unverifiable from runtime metadata, and a
CPU-offload compute path; only the 12B pair is a clean same-base,
all-GPU contrast. All inferential results are exploratory (no
preregistration, single run per cell, no multiplicity correction). See
`CLAIMS_MATRIX.md` before reusing any claim.

## Public artifact boundary

This public package excludes verbatim task prompts, generated output text,
raw row-level request records, local paths, and the private internal
archive. It retains the paper, processed measurements, per-family and
paired statistics, environment and model digests, the deterministic
analysis script, and SHA-256 hashes that identify every excluded raw
artifact (`data/RAW_ARTIFACT_HASHES.sha256`). The evaluation harness is
public at `github.com/mobius-style/mmv` (`operate-fr-bench/`); the
OPERATE-FR suite items themselves are project-local and identified by hash
in `ENVIRONMENT.md`.

## Layout

`PAPER.md` — full study. `EXECUTIVE_SUMMARY.md` — condensed findings.
`CLAIMS_MATRIX.md` — claim-by-claim evidence boundaries.
`REPRODUCE.md` — commands and artifact map. `ENVIRONMENT.md` — pinned
environment, model digests, suite hashes. `data/` — processed tables and
statistics. `analysis/` — deterministic analysis script (Apache-2.0).
Licensing: see `LICENSE.md` (split license).