experimentalCardEaseFactor

Dynamically adjusts ease factor on cards automatically after each rep, constantly seeking the right ease adjustment to hit a target success rate.

WARNING: Please note I currently lack the capacity to test new patches and features. Very sorry, but welcome forks from anyone who can take this on.

See: eshapard's "Thoughts on a new algorithm for Anki for the original rationale.

Important: You must NOT/NOT use an interval modifier in your deck options. Your interval modifier MUST be set to 100% (no change) for all decks. Otherwise this algorithm could be constantly chasing a moving target.

Differences from eshapard's version

Unlike eshapard's version, which requires four reviews before the algorithm kicks in, this version lets the algorithm adjust ease factors as early as possible, including using information from learning steps. Early data is less reliable, though, so we do two things: we limit how much the algorithm can change the ease factor at first, and we use a moving average to more heavily weight recent reps when calculating success rate.

If it took you a long time to learn a card originally, but now you've really got it down, your ease will rebound very quickly. The 'leash' setting ties your ease factor down at first, which limits the initial swings of the algorithm until you've had many more reviews and better quality data.

If you're used to ease factors very close to 250%, without a low leash, this algorithm can produce some alarmingly low (or high) ease factors. It will generally auto-adjust very quickly based on your performance though.

My anecdotal experience is that it front loads the work a bit, causing more reviews with short intervals in the beginning for hard cards, but backing off quickly after I know a card well.

Installation

In Anki,

Tools > Add-ons > Get Add-ons...

Then use this code:

1672712021

Manual installation

Create a new folder named autoEaseFactor in your Anki addons directory. Save all add-on files to this folder. If you don't want to use Two Button mode, it's still recommended you include the file to prevent errors, but you can simply disable this mode in settings.

Configuration

There are a few options that can be configured by editing the addon:

1. 'target_ratio' is the success rate you want to aim for (e.g. 0.85 for an 85% success rate)
2. 'leash' controls how much the ease can change per review, so a small leash of 10 or 50 will not let the algorithm adjust things until it has much more data.
3. moving_average_weight indicates how much to focus on more recent results when determining success rate. Higher numbers will focus more on recent performance. (This is very sensitive, values between 0.07 and 0.3 are reasonable).
4. min_ and max_ ease set the bounds of how far the algorithm can set the ease. This is "per mille," so 5000 = 500%.
5. two_button_mode makes the system "pass/fail" -- you can disable that by setting this to false (though saving mental load on each review is the primary benefit of this add-on, so I would recommend you leave this true if you can).

Two Button Mode

Hard and easy add more choices that delay reviews and make you responsible for determing your ideal ease rating. The ease factor algorithm adjusts ease for you, so you just need to choose either "Again" or "Good" on any given card.

The Two-Button file in the addon changes your options to Pass/Fail to help streamline your self evaluation, similar to low-key Anki and ja dark's work that inspired it.

I suggest that you use the TwoButton addon and that you disable Show next review time above answer buttons in Tools > Preferences... The next review times are misleading, they don't take into account the adjustments from this add-on and can distract you from studying.

If you just want to try this out, but you're worried about losing all the ease factors you've built up so far, the latest version lets you export a deck's current ease factors and re-import them later. You could use that to "save" your ease settings for a deck, try this add-on, then if you don't like it, reload your old ease settings later. Hat tip to RisingOrange for the inspiration, also check out his add-on: Reset Ease Automatically: https://ankiweb.net/shared/info/12081346

Acknowledgments

• eshapard
• ja-dark
• cordone
• risingorange
• the MIA crew
• the AnKing

I am not requesting support, but the original author, eshapard, can receive tips at this link: https://paypal.me/eshapard/1

Changes

2020-09-14

Add import/export ease settings to deck options (plus some bugfixes associated with that change).

2020-09-07

Rebrand, compatibility with latest version of Anki.

2020-08-23

New ease factors now incorporate the current review instead of looking only at historical reviews in the review log, and rely on the list of ease factors directly instead of deriving that information by comparing historical intervals. This should be more accurate in almost every case, but would throw off somebody who is continually rescheduling cards. Please provide feedback on github if this creates any unexpected results.

2020-08-09

Bugfix for formatted stats on new cards

2020-08-08

Slight formatting adjustment for stats. Also updates "tests[.]py" to be more accurate. Unfortunately "tests" still does not predict the algorithm's behavior exactly. I am expecting a better simulator next patch, after some additional debugging. (In the meantime, if you open "tests[.]py" and hardcode a list of ease factors, as in the commented-out example from lines 272 to 279, you will get an accurate simulation.)

2020-08-06

Adding four-button mode as an option, for those who don't want to use the Pass/Fail mode. I'd caution against using this though, the algorithm's main benefit is reducing your thinking time on each card.

(More history on GitHub: https://github.com/brownbat/autoEaseFactor )