95% of Quantum Country questions produce no lapses for most readers’ first half year

The flip side of Half of all long-term Quantum Country lapses come from just 12% of its questions is: across the whole site, the “easiest” 50% of questions account for only 10% of total long-term lapses. (Where a lapse is defined as forgetting after having already demonstrated five days of retention)

Slicing by essay, we see a bit more variability but the same general picture. The “easiest” 50% produce X% long-term lapses:

• QCVC: 13%
• Search: 14%
• Teleportation: 4% (!)
• QM: 8%

After two weeks of demonstrated retention, same story:

• Site-wide: 11%
• QCVC: 12%
• Search: 14%
• Teleportation: 3%
• QM: 10%

Most questions produce no lapses for most readers

But remember that Quantum Country users rarely forget after demonstrating five-day retention, so in absolute terms, that means most questions are forgotten very rarely. 20210325111014

Across Quantum Country, 95% of questions produce zero lapses for most readers’ first half year. Essays are very consistent here: slicing by essay produces 94-96%.

Extending the timeframe to one year: 93% of questions produce zero lapses in most readers’ first year.

Different thresholds:

• The “easiest” 52% of questions produce zero lapses for 90% of readers’ first half year
• The “easiest” 77% of questions produce zero lapses for 75% of readers’ first half year

Summed across all users

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• A 10th percentile question (in terms of lapses produced) produces only 4 lapses after it’s hit 5-day demonstrated retention—total! That’s out of 236 users with a history of at least half a year with that question.
• The 50th percentile question has produced 36 lapses over 339 students—about one total lapse for every ten readers.
• At the 90th percentile, we see 251 lapses over 348 students.

So what?

The review schedule is probably much too conservative the vast majority of the time. But on the other hand: Quantum Country’s high recall accuracy rates may mask forgetting because of cuing.