Although large segments of the population have access to the internet, those with no access were by default excluded from the sample. Internet penetration levels vary by country and are lower among certain segments of the population, notably elderly people, those living in remote areas and people with low education. Taking part in an online survey also requires digital literacy. Additionally, people who do not use any of the social media channels, where the e-survey was promoted, will not have exposure to the survey, unless they receive it from other participants via snowballing. It is not possible to correct for the bias that is introduced by these factors.
Respondents who agreed to participate in later rounds of the e-survey were asked to submit their email address (this data was pseudonymised and cannot be linked to their survey data), and were invited to participate in subsequent survey rounds. Over 50,000 panel members participated in multiple rounds of the e-survey.