Bonsall and his co-authors (Bonsall et al. 2012) applied
time series methods to self-rated depression data from
patients with bipolar disorder. The focus of their study was
mood stability: they noted that while treatment has often
focused on understanding the more disruptive aspects of
the disorder such as episodes of mania, the chronic weekto-
week mood instability experienced by some patients is
a major source of morbidity. The aim of their study was
to use a time series approach to describe mood variability
in two sets of patients, stable and unstable, whose members
are classified by clinical judgement. The time series
data were obtained from the Department of Psychiatry in
Oxford and was from 23 patients monitored over a period
of up to 220 weeksa. Patients were divided into two sets
of stable and unstable mood based on a psychiatric evaluation
of an initial 6-month period of mood score data.
Their classification into two groups was made on the basis
of mood score charts and non-parametric statistical analysis
which is described further in (Holmes et al. 2011). The
depression data for each group was then analysed using
descriptive statistics, missing value analysis (including the
attrition rate) and time series analysis.