# Glossary:D-Factor

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- D-Factor
- decline of O-Factors with successive repetitions can be approximated with a power curve that begins at O-Factor that equals A-Factor. D-Factors are no longer used in SuperMemo Algorithm. When a power regression is used to compute O-Factors on the basis of R-Factors for successive repetitions in a single A-Factor category, the decay constant of the resulting function is called a
**D-Factor**. You can see individual**D-Factors**for all A-Factors in**Toolkit : Statistics : Analysis : Graphs : D-Factor vs. A-Factor**. The larger the**D-Factor**the faster the decline of O-Factors with each repetition. This means that large**D-Factors**imply more frequent repetitions in a given difficulty category. Naturally, over time,**D-Factors**tend to be lower for easy item categories (unless O-Factors hit their minimum value of 1.2 for very difficult items).*D*in D-Factor stands for*decay*(it is a decay constant of the negative power function)