The most valuable thing the Dartmouth team built wasn't the grader. It was the fact that they could answer "did completing this lesson's quiz correlate with doing better on the exam?" — per module, per format. That question is why they discovered multiple-choice quizzing produced no measurable learning while constructed-response did. Without per-lesson dosage logged against exam outcomes, that finding is invisible, and the platform ships the useless format forever because everyone felt engaged.
This is post 7 of the assessment-first series. It's about the least glamorous and most compounding part of doerkit: the telemetry that lets the platform measure itself.
Dosage is the variable that matters
Most edtech analytics report engagement — logins, time-on-page, questions attempted. Those are vanity metrics; they measure whether people showed up, not whether showing up did anything. The variable the Dartmouth study built its whole argument on is dosage: how many lessons a student actually completed, regressed against exam performance. The distinction is the entire finding: engagement was comparable-or-higher under multiple-choice, but dosage only tracked exam scores under constructed response. If you log engagement you learn nothing; if you log dosage you learn which features work.
