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3. Blinding: Participants and personnel
Common error
“No blinding of participants or personnel but the outcome was objective therefore low risk” (e.g. clinical pregnancy or live birth)
• Participants can still influence their probability of an objective outcome via knowledge of allocation, e.g. a trial of IUI vs natural conception in couples with 3 years unexplained infertility
Whether the outcome is objective or subjective is relevant to outcome assessment (different domain).
3. Blinding: Participants and personnel
Common error
“It was not possible to blind participants due to the nature of the intervention therefore low risk”
e.g. IUI vs intercourse
e.g. hysteroscopy vs no hysteroscopy before IVF
Actually it is usually possible to blind participants, even if difficult and/or potentially unethical. And failure to do so still causes bias!
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PRECONGRESS COURSE 17 I VIENNA, AUSTRIA – 23 JUNE 2019 53
