Sentence examples for are often difficult to ascertain from inspiring English sources

However, the virus is not bound by vows of fidelity and behavioral characteristics of sexual partnerships are often difficult to ascertain due to recall bias and willingness of some persons to report sensitive behaviors such as concurrent partnerships.

However, the true incidence rates are often difficult to ascertain, due in part to difficulties in obtaining death certificates as well as the accuracy on the certificate itself (SCD is often unwitnessed).

Are these concepts applicable to the cyber domain where attribution of the attack is often difficult to ascertain and the range of cyber attack damage can be from the trivial (e.g., slowing email receipt) to the profound (e.g., disabling the nation's military early warning systems)?

Work in the past decade has more fully documented the mutational landscape in lymphomas, but the impact of these genomic lesions is often difficult to ascertain.

It is often difficult to ascertain whether the same composer created both the words and the music in a folk song; many songs are known to have separate sources for words and music.

In animal models it is relatively easy to demonstrate the therapeutic effectiveness of acupuncture, whereas in controlled clinical studies, it is often difficult to ascertain the specific effect of treatment.

It is often difficult to ascertain how long a hole has been present.

This is often difficult to ascertain, as many paraneoplastic syndromes can precede the discovery of associated tumor by years [ 2].

However, our results may be applied in the community setting where gestational age is often difficult to ascertain.

It was often difficult to ascertain, from the included studies, when these policy changes had taken place and therefore to discern the impacts of these policies, if any.

Hence, it is often difficult to ascertain that a given genetic population structure is natural rather than the result of anthropogenic modifications.