Figure 2: Panel (i) Visual representation of vectorized
monthly activity. All units are radians, not degrees. Months are placed
radially on a circle, with January at 0 radians. For each monthly
vector \({\overrightarrow{v}}_{i}\), the magnitude of the vector
is the number of vocally active hours per month, and the direction of
the vector is dictated by the month’s identity. These monthly vectors
are used to calculate R. Panel (ii) Visual representation of the
directional agreement between years. Panel (iii) Visual representation
of the magnitude of the sum of all vectors versus the total magnitude of
all vectors.