Entry 254-1 Build in Public 1 min ↩ back to the timeline

Measuring fluency

Juan goes down the rabbit hole of how language level is actually scored, and comes back with a sinsabor: there's no gold standard, only competing approximations. The signals that seem to work: higher levels (C1, C2) show up as complex sentences, less-frequent vocabulary, and abstract 'ethereal' images rather than concrete ones ('the boy fell'). Essay complexity, the fancier your lexicon and grammar, the higher your score, which is exactly how a teacher grades a composition. LLMs turn out to be reliable at scoring text: he had ChatGPT write a C2 passage and ChatGPT, Claude, and Gemini all graded it back around C1-C2. For the other skills he'll use rougher thresholds: listening by words-per-minute (A1 60-80, C2 180+), speaking by response time (A1 3-6 seconds, A2 2-4). He dislikes the hand-tuned thresholds but calls it a start, and dreams of the real fix: a GeoGuessr-style global ranking where users translate the same phrases, a scientific ranking instead of an empirical guess.

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// trace: where this idea came from

Having decided the reflex is the second phase, Juan went looking for how language level is actually scored, and came back with a sinsabor: there’s no gold standard, no single indicator everyone agrees on, only competing approximations ▸ 8:00. The signals that seem to work are about complexity. Higher levels show up as complex sentences, less-frequent vocabulary, and abstract images rather than concrete ones; “the boy fell” is a picture you see at once, an Aristotle reference is not ▸ 8:53. It’s the same thing a teacher does grading a composition, the fancier your lexicon and grammar, the higher the mark, which he half-dislikes but concedes works ▸ 11:37.

no hay regla de oro; la fluidez se mide en velocidad y complejidad →

For text, LLMs turn out to be reliable graders: he had ChatGPT write a C2 passage, then fed it back cold to ChatGPT, Claude, and Gemini, and all three scored it around C1-C2 ▸ 15:03. For the other skills he’ll use rougher thresholds, the hand-tuned kind he doesn’t love but calls a start: listening by words per minute (A1 around 60-80, C2 past 180), speaking by response time (A1 three to six seconds, A2 two to four) ▸ 15:53. What he really wants is to stop guessing: a GeoGuessr-style global ranking where users translate the same phrases and sort themselves against each other, a scientific ranking instead of an empirical one ▸ 19:03. Measure the transition, don’t declare it…

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