QuestionSBA
QuestionChoice
Although double-blinding is a feature used in many randomised control trials, we do not know if this has been done here, and therefore cannot expect this as the likely reason for the discrepancy.
10004712
b
The randomised control trial was double-blinded
QuestionChoice
If the measures of health outcomes used here were definitely subjective, for example, self-reporting symptoms on a questionnaire, this could lead to false reporting by subjects. However, we do not know what health outcomes have been measured here. For example, objective measures such as antibody levels could not be falsely reported by the subject.
10004714
d
Subjects are more likely to lie about their health outcomes in an observational study
QuestionChoice
Using more participants increases the sample size of a study, which can affect the results of the study. The key difference between the two study designs in this example is that the randomised control trial allows minimising of confounding factors that may have influenced the findings in the observational studies. Also, we do not know the sample size used in either study, so cannot comment on this.
10004715
e
The randomised control trial used more participants, so its results are more reliable
QuestionChoice
Although this is a possibility, this is unlikely, and it is far more likely that the randomised trial has removed the effect of confounding factors seen in observational studies.
10004713
c
The randomised control trial produced an anomalous, incorrect result
QuestionChoice
One of the major advantages of a randomised control trial is that it minimises (or even eliminates) the effect of confounding factors, which may have been present in observational studies.
10004711
a
The randomised control trial minimises the effect of confounding factors, which most likely were present in the observational studies
Concept
Chapter
2693
4322
Properties of meta-analyses
Topic
178
Medical Statistics
13489
Observational studies have shown that the health outcomes of patients receiving vaccine A are better than those of vaccine B, however, a randomised control trial shows no difference.

Which of the following describes the most likely reason for this discrepancy?
a