How the measurements work
Quantified Cognition uses your Anki review history to estimate daily recall and memory formation. It compares your answers with Anki's FSRS predictions, so the scores account for how likely you were to remember each card and how long it had been since you studied it.
Recall: how you performed that day
For each card, the add-on uses your first answer on an Anki day. Again counts as a failed recall; Hard, Good and Easy count as successful recalls. It compares each outcome with the predicted chance of remembering and averages the differences across the day.
A score above zero means you recalled more than predicted; below zero means less than predicted. Scores are expressed in percentage points. For example, if 80 successful answers were predicted across 100 eligible cards and you answered 85 successfully, the score is +5 percentage points.
Formation: what later reviews tell us about a study day
For each card studied on a day, the add-on looks at your first answer on the next Anki day when you review that card. It compares that answer with the FSRS prediction after your last review on the earlier day, allowing for the actual time between reviews. The difference contributes to the earlier day's formation score.
If you study a card on Monday and review it again on Friday, Friday's answer helps estimate Monday's memory formation. The daily score averages the available follow-ups. It is shown overall and separately for follow-ups within 30 days and beyond 30 days.
Cards awaiting another review are shown as pending, outside the score until a follow-up is available. Coverage shows how much of a study day's result is available. Scores become more complete as cards are reviewed again, with longer follow-ups taking more time to accumulate.
Sleep stages, naps and activity
Personal insights compare your daily scores with sleep and activity from the same periods of your history. Recall is compared with the preceding main sleep. Formation is compared separately with the main sleep before and after studying. Actual sleep-session times distinguish main sleep from naps, whose timing, duration and stages are examined separately. Steps use the previous day for recall and the study day for formation.
Comparisons between light, deep and REM sleep use the same eligible days and account for total sleep duration. For example, an estimate for ten more minutes of deep sleep replacing light sleep compares a change in sleep composition while holding total sleep and REM sleep constant. Oura and Google Health measurements are analyzed separately.
Uncertainty and interpreting changes
Scores include review counts, follow-up coverage and uncertainty intervals. Personal insights also show uncertainty and identify when there is insufficient data. Estimates depend on both the number of usable reviews and the number of days they represent.
Existing history is recalculated with your current FSRS settings. This allows older reviews to be analyzed, including eligible reviews from before FSRS and reviews synced from other Anki apps. Reviews that cannot be reconstructed reliably are excluded with a reason. Changing FSRS settings can change past scores. Dates use your configured Anki day boundary.
These scores estimate learning and recall relative to FSRS predictions. Card content, study routines, scheduling and conditions at the later review can also affect them. The comparisons can help identify patterns worth exploring in personal experiments. Establishing cause and effect also requires an appropriate experimental design.
The research information explains voluntary participation, and the privacy policy describes the data used and shared.