"this observation was seen" is correct and usable in written English.
You can use it in a sentence that is talking about something that the speaker or writer noticed. For example, "This observation was seen during the experiment, leading us to the conclusion that..."
This observation was seen consistently in the reviewed studies.
This observation was seen in both renal and hepatic impairment models, but it was more profound in the latter.
This observation was seen with the addition of either irinotecan or oxaliplatin, but the association with improved survival was stronger with irinotecan.
This observation was seen with all particles, regardless of size and surface modification and suggests that these particles are unable to disrupt intercellular junctions and traverse the alveolar epithelial barrier via the paracellular route.
This observation was seen across all diagnostic groups except AML and is consistent with recent international and UK data on ALL (Schroeder et al, 1995; Chessells, 1998; Lawson et al, 2000; Chessells et al, 2003; Roy et al, 2005), although our population-based study, as well as other diagnostic groups, included a longer follow-up period.
This observation is seen for variety of surface topographies and maximum contact pressures.
This observation is seen in other solid tumors including lung and breast [38].
One exception to this observation is seen with the HSA21 protein RCAN1.
Exceptions to this observation are seen in the deficiencies sDf130, which contains two distinct deletions, the smaller of which defines zone 10, and sDf128 which exhibits associated complexity.
An extreme of this observation is seen for K332, which shows no attenuation (left subpanel in Figure 2A, lowest trace Figure 2C), and thus this residue remains flexible both in free and when bound to TF.
This observation is seen across all cancer types, is applicable to both copy gains and losses, and is supported by the calculated genome-average background rates for CNAs as a function of length [ 1].
