Glossary:R-Factor

R-Factor - the number which says at which U-Factor (i.e. the measure of interval increase) the measured forgetting index (i.e. the measure of forgetting) is approximated to be 10%. This number is unique for different item difficulties and for different repetition categories (i.e. the measure of memory stability). R-Factors can be seen as a vertical green line on forgetting curve graphs in SuperMemo.