Spaced repetition selects words poorly

Implementation of SR in Duolingo is really lacking. My attention was drawn to it last week after about it decided that I have almost forgotten few hundred words in couple of days of missing practice (they were ALL marked as still strong before then). So I took a closer look at how the whole thing works.

To make sure I did not make a mistake I opened words list in two tabs (to have an initial state to check with) while going through flashcards.

Problem 1: Showing me cards that are already marked as "Still strong" when there are plenty which aren't.

The whole point of SR is that I practice terms that are in risk of being forgotten and not all of them. I've just been shown "corazón" which I have seen 2 weeks ago and currently is marked with 4 bars.

Problem 2: It shows words not on the wordlist.

For example I was shown "obligados" which does not appear on my list (neither does obligado or really anything starting with obli). More common variant of this is showing word in different gender. E.g. feminine instead of masculine when only later is part of word list. This would be fine if it recognized that it is still the same word. It doesn't so we come to...

Problem 3: Poor recognition of practices terms.

Gato, gatos and gata are basically the same term, differing only in quantity and gender. None of them are exceptions to the most common rule. Why I need to practice them separately is beyond me.

Similar problem with verbs, but at least I can see the point of practicing irregular verbs by tense even if this is a poor way to do it.

Problem 4: Practices words are not always marked as practiced

According to word list last time I practiced "ocupa" was a month ago. It isn't. It was this morning and I know this because before I practice, I reorder words on strength and ocupa is now in the third place of being ta most risk of forgetting. Since flashcards are position right enough that I can see the list, it wasn't difficult to notice when ocupa came up. Went through the whole pack (since cards are submitted only if stack is finished), but ocupa remains marked as unpracticed.

4/4/2016, 7:54:08 AM

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Excellent points. I am sure that I can learn a lot faster if they could improve the spaced repetition, so that I can practice the words that actually need practicing.

4/4/2016, 8:40:08 AM

Yeah, but hopefully duo can be like memrise and have many trees and improvements in the future.

4/4/2016, 8:37:31 PM
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I suspect that the "strengthen skills" exercises are intentionally padded with items that Duolingo considers to be easy.

For one thing, it would be frustrating to be quizzed exclusively on one's weakest skills. People wouldn't want to do such an exercise it if it were really difficult.

Another reason is to make sure that we can get to the end of a lesson! If we are making a lot of mistakes, I think it throws us some easy ones just so we can get the lesson over with and take a break.

I'm also beginning to suspect that Duolingo is trying to discourage cramming by annoying us with extremely easy items when we concentrate too much practice within a short time. Giving us items that are too easy doesn't hurt, but it is inefficient to drill what we already know, so it is a gentle way of telling us to cool it. This is just a guess.

4/8/2016, 3:59:13 AM
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I just use Anki, I have been using it since before using duolingo and find it very useful.

4/4/2016, 9:14:37 AM

I do too, but this bothers me also because I doubt that implementation of algorithm for selecting flashcards is completely independent from the one selecting which previously completed skill I need to refresh. Hence my study might be less efficient than it could be.

4/4/2016, 11:58:03 AM
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