A sample of symptoms that are depicted by the items includes sad mood, pessimism, loss of pleasure, self-blaming, loss of energy, and desire to commit suicide.
Studies that take samples irrespective of symptoms provide more information, but are methodologically difficult to implement [ 20].
Furthermore, the proportion of positive samples may be affected by the sensitivity of the test used, the sample type used and quality of obtaining the specimen, time of sampling after onset of symptoms and the patient groups sampled.
In studies involving non-clinical samples, careful measurement of symptoms of mental ill-health is important since such problems are often characterized by shifting patterns of symptoms that resist the precise classification used for clinical populations.
Partial verification bias is also noted in two studies whereby only a selected sample of patients' symptoms are verified by the reference test [ 24, 41].
Frequent assessment provides less biased and more representative sampling of patient symptoms, functioning and quality of life indicators than single assessments which are susceptible to recall bias and other errors [ 2].
After seven days of infestation (the time-point of sampling) symptoms of RM-infestation were clearly visible, but leaflets were not necrotic or senesced.
By sampling a range of symptoms, the development of the WHQ enabled examination of the relationships between these symptom clusters.
In non-forensic samples of adolescents, depressive symptoms are often identified as a significant risk for self-injury (Brunner et al., 2007; Garrison et al., 1993; Hilt, Cha, & Nolen-Hoeksema, 2008; Ross & Heath, 2003).
Altogether circa 2,400 samples of patients with symptoms of influenza like illness (ILI) were taken, of which 713 (30%) were found positive.
