Starting ease vs. interval multiplier

nomnex's Avatar

nomnex

24 Apr, 2013 05:23 AM

No offense, but I think this one is for Soren. because I am not confident I can understand this at once, or with a brief answer.

<Edit: I did not meant to be rude, but I should maybe reword the above. I called Soren on this one, because I am not sure Damien has time to go into a low level explanation. I often read Soren's replies along the list, and they often include detailed explanations and examples. I think that's what I need on this one.>

So far my use of Anki has been a failure. It's partly due to frequent and long interruptions, and partly due to my limitation understanding the scheduling. In fact, if I compare my use of Anki to a sports car, I can shift the gears, but I can't take a curve.

I give it another try, and I have a few questions coming up. If you think I should rather post them on the Anki-user group, let me know.

First, I fail to see the difference between the "starting ease" (New cards), and "the interval modifier" (Review cards)
-What are their respective purpose (ie. the difference between them)?
-How do they interact with each other?
-Why is there not only one, or the other, but both?

A. the starting ease
From what I understand, it allows me to change a card next interval, and it increase or decrease automatically according to my ratings.
"From the manual: It defaults to 250%, meaning that once you’ve finished learning a card, answering "Good" on subsequent reviews will increase the delay by approximately 2.5x (eg if the last delay was 10 days, the next delay would be 25 days)"

B. Interval multiplier
From what I understand, it allows me to change a card next interval too.
"From the manual: It allows you to apply a multiplication factor to the intervals Anki generates

Concretely: If I want to reduce the interval of my cards,I don't know if I should modify the "ease factor" (only), the "interval multiplier" (only), or both? (and of course, why?)

In the past, I used anki for 6 months regularly (with the default scheduling). The card intervals were growing too fast. I had a high failing rate (I have difficulty remembering a >2 weeks old material). To counter the increasing interval effect, I was answering "Again" or "Hard". It was pointless and demoralizing.

  1. 1 Posted by Aleksej on 24 Apr, 2013 07:59 PM

    Aleksej's Avatar

    (I've written this without reading your message at the same time, so it mostly repeats what you already know)

    Ease (factor) is a dynamic property of a card. It starts with "Starting Ease" (250% by default), and when you rate a card:

    • Good — the Ease stays what it was;
    • Easy — the Ease increases;
    • Hard or Fail — the Ease decreases.

    If you answer good, the next interval is the ease % of the last one.

    Starting Ease is the first ease for a newly introduced card. A card gets it only once. 250% was probably chosen as about the average ease of well-formulated cards (or not so well). Maybe it was chosen also with an intent to have a certain forgetting index — probably the 90% mentioned in the manual.

    If most of the new cards in a deck are easier than 250%, you will be choosing "Easy" all the time — and maybe their actual easiness is 290%, so you will be wasting time reviewing them. So you can set the starting ease to something higher. Alternatively, you could reschedule the cards (if you reschedule it too far, the card will later get an ease lower than the starting ease; that may be a problem, but you can mitigate it with the New interval setting for Lapses).

    If most of the new cards are harder than 250%, you will be choosing "Hard" or "Fail", also wasting time. So you can set the starting ease to something lower. However, according to the manual, the Easy button is pretty strong, so it may be normally easier to decrease the Ease by reviewing than it is to increase it, so cards which are actually easy may be stuck with an ease too low and use more time than is necessary.


    If I understand it correctly, "Interval modifier" hijacks the ease property: it is applied after all the other factors (except for sibling spacing) have been used in calculation. I think it changes the meaning of an ease value, so 250% means a different easiness in a deck with one modifier than in a deck with a different one. So if you use Ease to assess the easiness of a card, this may be confusing.


    Summary:

    • Starting ease affects cards at the moment they become review cards first. It should be obvious how it works.
    • Interval modifier affects cards on every review. I believe it may be confusing and changing it for a deck with existing review cards might cause more confusion. I'd change only Starting Ease if the deck has almost only new cards.
  2. 2 Posted by Soren Bjornstad on 24 Apr, 2013 08:56 PM

    Soren Bjornstad's Avatar

    First, I fail to see the difference between the "starting ease" (New cards), and "the interval modifier" (Review cards)

    Please see above for a good explanation of ease—it's a property each card has that controls how aggressively it gets scheduled into the future, and is modified based on every review of that card. The ease can be defined as the factor by which a card's interval is multiplied when you select "Good." By default ease starts at 2.5 (usually referred to as 250%), but you can change it here.

    The interval modifier is an additional factor that can be used when scheduling cards; if you set this to 80%, every interval will be decreased to 80% of its previous value, on every review, no matter what difficulty level you press (except Again), after the usual calculations based on the difficulty you select.

    Why is there not only one, or the other, but both?

    The starting ease is to be used if you introduce a batch of cards that are significantly harder or easier to pick up than normal. Lowering the starting ease is equivalent to having pressed "Hard" and "Again" a bunch of times and then started learning the card: the interval will begin to grow more slowly than usual. (Obviously the reverse is true for raising it.)

    The interval modifier is roughly equivalent to SuperMemo's "forgetting index": if you find that you're forgetting more material than you wish, it will cause all intervals to grow/shrink at a different rate than usual. However, it will not affect the ease at all.

    In general, I'd say the interval modifier is a bit more drastic, as its effects won't be reversed automatically over time if your cards prove to be easier or harder than you anticipated (although if you set the starting ease to 130% and start trying to learn more than a couple of cards per day, you'll probably be swamped even if you're constantly pressing Easy). However, that could also be a good thing.

    Concretely: If I want to reduce the interval of my cards,I don't know if I should modify the "ease factor" (only), the "interval multiplier" (only), or both? (and of course, why?) In the past, I used anki for 6 months regularly (with the default scheduling). The card intervals were growing too fast. I had a high failing rate (I have difficulty remembering a >2 weeks old material). To counter the increasing interval effect, I was answering "Again" or "Hard". It was pointless and demoralizing.

    My instinct would be to decrease the interval modifier in this situation, but I haven't experimented much with changing scheduling settings personally, so it might indeed be a good idea to ask on the users forum and see if anybody has tried both ways.

  3. 3 Posted by nomnex on 28 Apr, 2013 02:09 PM

    nomnex's Avatar

    Thanks to both of you. Just to let you know I read you with interest, and I am trying the interval modifier & the card ease on a few cards (unfortunately, I don't have no mature card yet). I will edit this post with some questions in a week or two. Soren, be kind to keep this thread open.

  4. 4 Posted by Soren Bjornstad on 28 Apr, 2013 02:49 PM

    Soren Bjornstad's Avatar

    Will do.

  5. 5 Posted by Soren Bjornstad on 17 May, 2013 06:06 PM

    Soren Bjornstad's Avatar

    If you have further information, feel free to reopen this.

  6. Soren Bjornstad closed this discussion on 17 May, 2013 06:06 PM.

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