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Benchmarking Qwen3.8 27B quantizations: 4-bit holds up, 1-bit collapses

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Re: Benchmarking Qwen3.8 27B quantizations: 4-bit holds up, 1-bit collapses

#131

> Second, besides noise (bars are Wilson 95% confidence intervals, very conservative for run-to-run noise), there is little difference down to 4-bit; only the 2-bit scores a bit lower. Confidence intervals have nothing to do with run-to-run variation. They have little to do with anything people usually ascribe to them ( https://link.springer.com/article/10.3758/s13423-015-0947-8 ), but even less with run-to-run varia…

Task success is not enough; reliability and cost matter.

Re: Benchmarking Qwen3.8 27B quantizations: 4-bit holds up, 1-bit collapses

#132
post #128

Measuring quality e2e definitely makes sense. But I think there is a bit more to this: > Measuring token prediction differences (KL-divergence, top-1 predictions) is easy, but it does not tell us whether the model gets worse at solving tasks. A common issue is that it's rarely mentioned on which dataset KL-divergence is computed. It seems the most common dataset is wikitext - maybe because of tradition, to make numbe…

Before this experiment I tried to run KLD on various context lengths to see a quantization-dependent deterioration. On wikitext2 there was no difference. I concluded these have no long-term dependency and I should use Linux kernel. Still, the same. So yes, KLD depends on the dataset. Still, it does not measure what any e2e test does.

Yeah, makes sense; e2e is different and valuable, KLD is not a replacement.

As for KLD, have you tried it on something which is even closer to e2e task, like agentic traces from https://huggingface.co/datasets/nvidia/Nemotron-Cascade-2-SF... or similar datasets?

Re: Benchmarking Qwen3.8 27B quantizations: 4-bit holds up, 1-bit collapses

#133
post #128

Earlier quoted context omitted.

Before this experiment I tried to run KLD on various context lengths to see a quantization-dependent deterioration. On wikitext2 there was no difference. I concluded these have no long-term dependency and I should use Linux kernel. Still, the same. So yes, KLD depends on the dataset. Still, it does not measure what any e2e test does.

Yeah, makes sense; e2e is different and valuable, KLD is not a replacement. As for KLD, have you tried it on something which is even closer to e2e task, like agentic traces from https://huggingface.co/datasets/nvidia/Nemotron-Cascade-2-SF... or similar datasets?

Nope.

If you would like to do so, it is easy (and orders of magnitude cheaper) than running benchmarks.

Re: Benchmarking Qwen3.8 27B quantizations: 4-bit holds up, 1-bit collapses

#134

Earlier quoted context omitted.

Your first link is just the pedantry. The second link... I don't see any issue for the question I asked? The confidence interval is supposed to be wrong a certain percent of the time. It being so wrong it disproves itself is funny but the 90% is still 90% isn't it? They just landed in a particularly harsh part of the 10%. The conclusion they come to is "it is possible to do better in the individual case by taking int…

If you just meant it in the sense that “if I pick one interval at random and don’t look at it, it will (future) have an n% chance of containing the true parameter” then sure. It’s a pre-data statement (“I have an n% chance of sampling data that will happen to generate an interval that contains the parameter”). But once you have picked one, and you know its bounds (say, [12.1471, 13.8264]), then it’s fallacious to mak…

I can see the analogy here but a test like that being binary throws things off and that's also super asymmetrical error. Weren't we sampling a gaussian?

Re: Benchmarking Qwen3.8 27B quantizations: 4-bit holds up, 1-bit collapses

#135
post #121

Measuring quality e2e definitely makes sense. But I think there is a bit more to this: > Measuring token prediction differences (KL-divergence, top-1 predictions) is easy, but it does not tell us whether the model gets worse at solving tasks. A common issue is that it's rarely mentioned on which dataset KL-divergence is computed. It seems the most common dataset is wikitext - maybe because of tradition, to make numbe…

> A common issue is that it's rarely mentioned on which dataset KL-divergence is computed. It seems the most common dataset is wikitext Thank you for calling this out. Using Wikipedia snippets for these is a terrible choice. I did a bunch of KL and other stats with the five Gemma 4 models, and the results were non-obvious. Anthropomorphizing: Gemma 4 31B: "I guess we'll pretend I said this, but it's not me." (Baselin…

> Anyway, for comparing quantizations, it seems like the largest precision version should be given a one-shot prompt, and the result from that should be used as the corpus for the quantized versions.

Way better than wikitext-- but tells you nothing about errors tending to compound or cancel out.

Like say a test shows that only one token in a 10,000 token test would be different. Sounds very close, ship it!-- but what if trajectories with that single different token guarantees failure because it sets in motion a cascade of differences that ultimately result in a final distribution that doesn't include the solution?

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