Smart Train
How Smart Train decides what you practise
Every position in your repertoire carries its own review date. Smart Train works out that date from how you have answered the position before, so the moves you keep missing come back quickly and the ones you know stop taking up your session.
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How it works
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A new position is due straight away
Anything you have never trained has no history to schedule from, so it goes to the front of the queue.
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The first two intervals are fixed
Answer correctly once and the position returns in about four hours. Answer correctly again and it returns the next day. These two steps are the same for every position, because two correct answers is not yet evidence of anything.
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After that the gap multiplies
From the third correct answer onward, the next gap is the previous gap multiplied by an ease factor. The ease factor starts at 2.5 and rises by 0.1 each time you get the position right, up to a ceiling of 3.5. So the gaps do not just grow, they grow faster the better you know the move.
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A miss resets the streak
Get it wrong and the position is due again tomorrow, and the ease factor drops by 0.2, down to a floor of 1.3. A position you keep failing will keep coming back roughly daily until it sticks.
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Deep moves are pulled forward
The interval is divided by a depth penalty of one plus five per cent per move of depth. A move fifteen plies into a line is reviewed noticeably more often than a move on the third ply, because there is more to forget on the way to it.
Under the hood The exact settings and constants. Not needed to use it.
- Starting ease factor
- 2.5
- Ease change per correct answer
- +0.1, up to 3.5
- Ease change per miss
- -0.2, down to 1.3
- First interval
- About 4 hours
- Second interval
- 1 day
- Later intervals
- Previous interval x ease factor
- Depth penalty
- Divided by 1 + (depth x 0.05)
- Longest gap
- 30 days
Answer a shallow position correctly every time and the gaps run roughly 4 hours, 1 day, 3 days, 8 days, 22 days, then 30 days from there on. The cap exists so nothing in your repertoire disappears from view for a whole season.
Why this method and not another
The spacing effect
Hermann Ebbinghaus established in the 1880s that material reviewed at widening intervals is retained far better than material reviewed at a constant rate, or crammed. Everything above is an application of that one finding to a position tree.
The testing effect
Being asked to produce an answer strengthens memory more than reading the same answer again. This is why training asks for the move and waits, instead of playing it for you and asking whether it looked familiar.
What we do not claim
We have not run a study on Chess Prep Pro users, so there is no percentage here. The method is well evidenced in the psychology literature. How much it helps you depends on how often you actually open the app.
What it will not do
- It schedules positions you have saved. It has no opinion on whether the moves in your repertoire are good ones, which is what the opening book and the engine are for.
- It cannot tell the difference between a move you knew and a move you guessed correctly, so an honest session is worth more than a lucky one.
- It needs regular short sessions. A month of nothing followed by an hour of catching up defeats the point of the schedule.
Try it on your own openings
Free to start, with no repertoire or move limit.
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