Interpreting mood scores: clinical implications of individual differences in mood variability

Mood variability is shown to be a stable characteristic of individuals, such individual differences accounting for some 25 per cent of the total variability of mood scores over time. This large effect is shown to have three major consequences: it is impossible to use tables of norms to assess the severity of a given mood for an individual; the whole logic of using norms for the interpretation of moods is flawed; and correlations between moods and traits have been underestimated in the literature. Various techniques are discussed for minimizing the effects of bias caused by individual differences in mood variability.