Short answer: a well-built short diagnostic doesn't measure everything — it samples. One question per core calculator skill, taken under one-try test conditions, is enough to rank which skills are shaky and which are solid, so your practice time goes where it pays. It is not a score predictor.
How the diagnostic works
Desvantage's diagnostic is 12 questions, each mapped to one core calculator skill: solving by graphing, systems, zeros, sliders, statistics, regressions, and so on. You get one try per question with a live calculator beside you — the same conditions as test day. At the end, each miss flags its skill as a predicted weak area, and each area links directly to the lesson and drill that train it.
Why one question per skill is enough
The goal isn't precision — it's triage. If you miss the systems question, one of two things is true: you don't know the calculator move, or you can't execute it quickly yet. Either way, the same fifteen minutes of drilling fixes it. A longer test would tell you the same thing more slowly.
What it can't tell you
- Your score. Twelve questions can't predict a composite. Anyone who claims otherwise is guessing.
- Content gaps. It measures calculator execution, not whether you know what a median is. If a definition itself is fuzzy, the lessons' plain-English key words help — but deep content gaps need review beyond calculator strategy.
- Luck. One guessed-right answer can hide a weak skill. Retake it after drilling and watch which areas flip.
How to use the result
Drill your two weakest areas first — the diagnostic links each one to its move. Retake it after a week of practice; areas that flipped from red to green are locked in, and whatever's still red is your next fifteen minutes. The diagnostic is free, no card required.