About FSRS algorithm's "first rating"

Anki FSRS
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Could like your help on several noob questions that pop up after reading on the algo on github, which presumably could be easily answered by experts within seconds.

All kinds of advice (including simple Y/N, or even I don’t know, hey most ppl don’t fuss) are appreciated.

Conside the following scenario, describing a single card in a deck with default learning steps “1m 10m”:

  • Card in “New” queue
  • (Moment 1)
  • (Moment 2) Choose “Good”.
  • Card in “Learning” queue
  • (Moment 3)
  • Ten minutes later.
  • (Moment 4) Choose “Again”.
  • One minute later.
  • (Moment 5) Choose “Good”.
  • (Moment 6)
  • Ten minutes later.
  • (Moment 7) Choose “Good”.
  • (Moment 8) Card graduated. Card assigned “Interval”, ie a due date.
  • Some “Interval” later, card in “Due” queue.
  • Review that card.
  • (Moment 9) Choose “Good”.
  • (Moment 10) Card in “Due” queue.
  • (Moment 10) Card assigned a new “Interval”, ie a due date.

Q1. Is there any mistake on the above simulation?

Using SM2, “Interval” at Moment 8 is derived based on decision at Moment 7 according to Studying - Anki Manual . It means there are only two valid ease: “Good” (shown again the next day) and “Easy” (shown again 4 days later).

Using FSRS 4.5 Anki 24.06.3

Q2. What is the “first rating” moment? Which decision the “Interval” at Moment 8 is derived from? Moment 2, 5 or 7? I think the answer’d be Moment 7, bc all decisions in “Learning” queue should not affect “Interval” right?

The algo doc says … initial stability when the first rating is again …

Q3. What is a “Again” first rating? How can a card graduate upon “Again”?

Given the default FSRS 4.5 parameters, if I answered “Again” at Moment 2 (the very first decision) and then “Easy” at Moment 7 (the gradating decision). What is the Stability value if any,

Q4. At Moment 1? and
Q5. At Moment 8? (the essential question)

Lastly, I am unsure but I recall reading about addition of new short-term memory parameters in the most recent algo,

Q6. Does FSRS v 5 have feature that could change the answer to Q2 ? Is it implemented in Anki 24.10 beta?

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  • “Review” a new card in a deck with default learning steps “1m 10m”.

That’s it, that’s the moment when the next interval is decided. You didn’t specify the grade (Again/Hard/Good/Easy), but anyway, that’s when the interval length in FSRS-4.5 is determined, the rest is irrelevant. FSRS-5 has some extra formulas for handling same-day reviews, but overall it’s only mildly more accurate than FSRS-4.5. Same-day reviews have a very small impact on long-term memory, this conclusion is based on benchmarking lots of algorithms, not just FSRS.

Basically
FSRS-4.5: use the first review of the day, ignore the rest.
FSRS-5: use the first review of the day using the main formula, use the following same-day reviews via the new formulas.

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4

No, but I suspect you don’t understand the word “queue”. In moment 10, the card isn’t in any queue. It’s simply not due yet, it’s in the queue if its due and you ca study it. AFAIK that’s how the word is used but it’s really not needed to understand all this.

There are two possible graduating intervals. Ease is different in SM2.

Moment 2.

If you click Again on a new card that’s the first rating. The ratings after that do not count (unless you’re doing them in a different day).

It is in the new beta.

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5

I interpreted

  • “Review” a new card in a deck with default learning steps “1m 10m”.

literally. Like, you know, reviewing a card. Doing a review. But I’m starting to think that OP meant something else entirely.
Anyway, OP, if you meant “review” in the literal sense, then that’s the moment when the first interval is decided with FSRS-4.5. If you meant something else and you actually meant that the first time you click an answer button is what you call “Moment 2”, then Moment 2 is when the first interval is decided with FSRS-4.5.

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6

Thank you all!

So on grading / response decision’s effect on scheduling for long term memory retention.

With SM2,

  • In a “Learning” queue, only the graduating grading on a card affects scheduling. Arbitrary algo is used.
  • All subsequent gradings (in “Due” queue) also affect scheduling unless otherwise configured.

With FSRS,

  • Only the first grading of each day affects its scheduling regardless of the queue it is in.
  • All other gradings, including subsequent gradings within “Learning” queue before a card graduates, do not affect scheduling (FSRS 4.5) or have mild effect (FSRS 5), provided the learning process finishes within the same day.
  • The same day config should be viewed as a constraint related to the scientific research settings that FSRS is based on, where it is assumed when test subject goes to sleep, a day boundary is crossed. It should not be viewed as a causal recommendation aimed to prevent interval miscalculation on Anki.

Now, to answer Q5 : Given the default FSRS 4.5 parameters, if I answered “Again” at Moment 2 (the very first decision) and then “Easy” at Moment 7 (the gradating decision). Answer The Stability value at Moment 8 = 0.4872. “Easy” at Moment 7 (the gradating decision) is irrelevant.

Thanks for clarifying “queue” and “review” word usage, edited just now. Yea I meant studying one new card. (A confusing word choice, been playing around “reviewer.py” addon).

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I don’t think that’s how the word “queue” is used either. IIRC queue refers to this:
image