2.5 Bias
As the survey was distributed online via a UK-based charity, there is a selection bias towards the members of the charity, members with internet access and UK residents. In addition, individuals with more significant olfactory dysfunction may be more likely to respond. There is a risk of response bias as participants tend to agree or provide positive answers in, e.g. in rating scales and yes/no questions. We aimed to mitigate this issue by incorporating free text boxes to allow participants to be more nuanced.