Limits and uncertainty

Check the precision, confounding, boundaries, and known unknowns before treating the finding as settled.

A blog post says spaced repetition improves retention "by 40%," and you're about to rebuild your entire study system around that number. A single confident percentage is doing an enormous amount of work here, and you haven't yet asked what's standing behind it.

The move is to check the precision, confounding, boundaries, and known unknowns before treating a finding as settled. The cue is a clean point estimate presented without a range or conditions. Steps: find the spread behind the number (40% plus or minus what, across which studies?), ask what else differed between groups (motivated volunteers reviewing anything beats no review), locate the boundaries (the gains show up for fact and vocabulary recall, not necessarily conceptual understanding), and name what remains unknown (long horizons, your specific material). When it works, the number becomes a bounded claim, "helps with fact recall, size uncertain," and your adoption becomes proportional: you add flashcards for vocabulary without tearing down everything that already works. Don't demand more precision than the decision needs; a free habit with plausible upside deserves a lower evidence bar than a curriculum overhaul, and stalling cheap experiments in the name of rigor is its own failure.