Repetition history

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With Learning : Statistics : Repetition history (Shift+Ctrl+H) available from the element menu you can quickly display the history of repetitions for the currently displayed element.

SuperMemo: Repetition history dialog box displaying the history of repetitions for the current element

Figure: Repetition history dialog box displaying the history of repetitions for the current element related to the Malpighian body and the renal tubules. In this example, the item has been repeated 10 times thus far. It was forgotten only once at the 3rd repetition on Apr 20, 1999 (after 97 days since the previous repetition). Since then it has been recalled successfully every time. It was last repeated on Apr 01, 2019 at 12:08:57. The hour data is present only for the last repetition due to the fact that SuperMemo registers the repetition hour only as of SuperMemo 13 onwards (hours are used in correlating retention with sleep data available from SleepChart). The item is scheduled for repetition in roughly 4.5 years (on Sep 18, 2023)

Data columns

  • No - the number of times the element was repeated/reviewed. (f) to the left of any given repetition number indicates the repetition when the item was forgotten (i.e. you were not able to provide the correct answer). In the example above, the item was not recalled at the 2nd repetition.
  • Rep - the first figure represents the number of consecutive successful repetitions (when you graded yourself Pass (3) or higher). The other one shows the cumulative number of times you did not remember the Item (i.e. your grade was Fail (2) or less) since you first memorized it. Note that each time you forget the answer, the first figure gets reset to 1.
  • Date - the date when you repeated/reviewed the element, or, when it is scheduled for the next repetition (Next at the top)
  • Hour - the time (hh:mm:ss) when you repeated a given element
  • Grd - the grade that you gave yourself at a given repetition. Since you do not grade yourself on topics, the column reads Topic for this type of element
  • Interval - the number of days between successive repetitions: the one from the preceding row and the one from the current row
  • Prior - the relative position of the element in the priority queue at the time of the repetition (the lower the number, the higher the priority)
  • Difficulty - element's difficulty after a given repetition
  • S - element's stability after a given repetition
  • R est. vs. R - retrievability as computed with the DSR model (Algorithm SM-17), and retrievability derived from the expected forgetting index (Algorithm SM-15). Darker fields show higher predictive differences
  • Dev - retrievability deviation: the disparity between retrievability and actual recall expressed with the default metric (as percent)
  • Postp. - the number of times the element was postponed until a given repetition

Context menu

Right-click over the Repetition history window opens a context menu with the following items:

  • Edit (Ctrl+E) - edit the repetition history (this may affect the algorithm and sleep optimization)
  • Copy (Ctrl+C) - copy the element's repetition history to the clipboard
  • Delete (Del) - delete the element's repetition history (after confirmation)
  • Save (Ctrl+S) - save the repetition history if it has been corrected for errors
  • Close (Esc) - close the repetition history window
  • Memory status (F2) - visualize changes in memory retrievability and stability over time
  • Fix and Edit - correct errors in repetition history before editing. The latest algorithms put a premium on the correctness of repetition histories. Some data errors inherited from older SuperMemos would be uncovered in SuperMemo 17 or later (e.g. in multiple dismiss/reset operations, postpones, fake date settings, etc.). Raw repetition history data can be edited, however, it may be more convenient to do basic error correction by SuperMemo before the editing. Fix and Edit does error recovery and only then presents data for editing

SuperMemo: Changes in two components of long-term memory

Figure: Changes in memory status over time for an exemplary item. The horizontal axis represents time spanning the entire repetition history. The top panel shows retrievability (tenth power, R^10, for easier analysis). Retrievability grid in gray is labelled by R=99%, R=98%, etc. The middle panel displays optimum intervals in navy. Repetition dates are marked by blue vertical lines and labelled in aqua. The end of the optimum interval where R crosses 90% line is marked by red vertical lines (only if intervals are longer than optimum intervals). The bottom panel visualizes stability (presented as ln(S)/ln(days) for easier analysis). The graph shows that retrievability drops fast (exponentially) after early repetitions when stability is low, however, it only drops from 100% to 94% in long 10 years after the 7th review. All values are derived from an actual repetition history and the DSR model.