Difference between revisions of "File:First forgetting curve.jpg"

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{{Fig|The first [[Glossary:Forgetting curve|forgetting curve]] for newly learned knowledge collected with [[SuperMemo]]. Power approximation is used in this case due to the heterogeneity of the learning material freshly introduced in the learning process. Lack of separation by [https://supermemo.guru/wiki/Memory_complexity memory complexity] results in superposition of exponential forgetting with different decay constants. On a semi-log graph, the power regression curve is logarithmic (in yellow), and appearing almost straight. The curve shows that in the presented case recall drops merely to 58% in four years, which can be explained by a high reuse of memorized knowledge in real life. The first [[Glossary:Optimum interval|optimum interval]] for review at [[Glossary:Retrievability|retrievability]] of 90% is 3.96 days. The [[Glossary:Forgetting curve|forgetting curve]] can be described with the formula R{{=}}0.9907*power(interval,-0.07), where 0.9907 is the recall after one day, while -0.07 is the decay constant. In this is case, the formula yields 90% recall after 4 days. 80,399 repetition cases were used to plot the presented graph. Steeper drop in recall will occur if the material contains a higher proportion of difficult knowledge (esp. [https://supermemo.guru/wiki/20_rules poorly formulated knowledge]), or in new students with lesser mnemonic skills. Curve irregularity at intervals 15-20 comes from a smaller sample of repetitions (later interval categories on a log scale encompass a wider range of intervals).}}
'''''Figure:''' The first [[Glossary:Forgetting_curve|forgetting curve]] (first [[Glossary:Repetition|repetition]] for [[Glossary:Item|items]] with no [[Glossary:Lapse|lapses]]). Unlike it was the case in earlier SuperMemos, where all [[Glossary:Forgetting_curve|forgetting curves]] were exponential, the first forgetting curve in SuperMemo 18 is approximated using power regression. This provides for a more accurate mapping due to the heterogeneity of the learning material introduced in the learning process that results in superposition of exponential forgetting with different decay constants. The use of power regression explains why the first [[Glossary:Interval|interval]] might be slightly shorter in [https://supermemo.guru/wiki/Algorithm_SM-17 Algorithm SM-17]. On a semi-log graph, the power regression curve is logarithmic (in yellow), and appearing almost straight. The curve shows that in the presented [[Glossary:Collection|collection]] recall drops merely to 58% in four years, which can be explained by a high reuse of the memorized knowledge in real life. In earlier SuperMemos, recall data would only be collected in the span of 20 days, and negatively exponential [[Glossary:Forgetting_curve|forgetting curve]] would make for far lower retrievability predictions. The first [[Glossary:Optimum_interval|optimum interval]] for the [[Glossary:Forgetting_index|forgetting index]] of 10% is 3.76 days. The [[Glossary:Forgetting_curve|forgetting curve]] can be described with the formula R=0.987*power(interval,-0.07), where 0.987 is the recall on Day 1, while -0.07 is the decay constant. This is case, the formula yields 89.5% recall after 4 days, which is then used as the first rounded optimum interval. Almost 77,000 repetition cases were used to plot the presented graph. Steeper drop in recall will occur in [[Glossary:Collection|collections]] with a higher mix of difficult [[Glossary:Item|items]], in poorly formulated [[Glossary:Collection|collections]], or in new users with lesser mnemonic skills.''
 
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Revision as of 09:59, 3 May 2019

Figure: The first forgetting curve for newly learned knowledge collected with SuperMemo. Power approximation is used in this case due to the heterogeneity of the learning material freshly introduced in the learning process. Lack of separation by memory complexity results in superposition of exponential forgetting with different decay constants. On a semi-log graph, the power regression curve is logarithmic (in yellow), and appearing almost straight. The curve shows that in the presented case recall drops merely to 58% in four years, which can be explained by a high reuse of memorized knowledge in real life. The first optimum interval for review at retrievability of 90% is 3.96 days. The forgetting curve can be described with the formula R=0.9907*power(interval,-0.07), where 0.9907 is the recall after one day, while -0.07 is the decay constant. In this is case, the formula yields 90% recall after 4 days. 80,399 repetition cases were used to plot the presented graph. Steeper drop in recall will occur if the material contains a higher proportion of difficult knowledge (esp. poorly formulated knowledge), or in new students with lesser mnemonic skills. Curve irregularity at intervals 15-20 comes from a smaller sample of repetitions (later interval categories on a log scale encompass a wider range of intervals).

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