Moreover, GROS pressure to ascertain accurate causation had itself 'tended to establish pathologists who [had] become quite keen on doing still births and neonatal deaths', and were 'considerably more expert than they were ten years ago'.
First, the cross sectional nature of both surveys means inability to ascertain temporality and causation between circumcision, sexual behaviour and HIV status.
Ignorance of reportable events, lack of awareness of a reporting system, insecurity regarding causation (not possible to ascertain whether the drug caused the reaction) and lack of time are common reasons associated with lack of reporting [ 14, 24- 28].
Of course, these are observational studies, and as such causation can be hard to ascertain.
Causation is quite intricate to ascertain than correlation in Pharmacovigilance due to numerous inherent shortcomings in causality assessment tools.
Causation is much more challenging to ascertain, particularly when the index presentation is with both AF and LV dysfunction.
Among them, due to the cross-sectional nature of this investigation, our results do not imply causation; longitudinal studies are needed to ascertain causality.
However, this was a cross-sectional study that cannot test causation, and is thus not possible to ascertain whether reduced knee flexion when landing, is a cause, or effect of, knee injury.
Similarly, there are a variety of types of leukemia, each probably with differences in causation, making it even more difficult to ascertain sufficient numbers of homogeneous tumors for study.
