The ratings from questionnaires (Pincus 2003) have
commonly been summarized using mean and standarddeviation although other measures have been used. Pincus
(1991) introduced approximate entropy as a measure of
time series regularity or predictability. It was applied
to both mood data generally (Yer-agani et al. 2003)
and to mood in bipolar disorder (Glenn et al. 2006),
where 60 days of mood data from 45 patients was
used for the analysis. It was also applied in another
study to distinguish between the pre-episodic and other
states (Bauer et al. 2011). A summary of papers which
report a temporal bipolar mood analysis is given in
Table 1.