Governments and public health authorities have placed several restrictions and recommendations to prevent the spread of COVID-19 but that has not stopped the pandemic. Since the first outbreaks various organisations run web surveys trying to understand attitudes and behaviours of citizens related to protective measures and with the advent of COVID-19 vaccines they extended the topic to vaccine hesitancy. Under time pressure due to the emergency of the health crisis, many of these surveys gave precedence to speedy results on the expense of survey quality. One of the common methodological problems is the use of convenience samples that do not allow the generalisation of results to the population instead of more representative options. In this contribution, I present two case studies of such cross-sectional surveys in Slovenia. The first was about compliance with protection measures such as social distancing and mask wearing and run in November 2020, while the second dealt with vaccination attitudes and was conducted in December 2020, just before the arrival of the first doses of the vaccine. In both studies the questionnaire was administered in parallel to two samples, a large snowball convenience sample and a smaller marketing panel sample that is representative of the country’s population. In both cases the comparison of results between the two samples indicates certain biases. Finally, the results are discussed considering other studies on the topic and recommendations are provided for how to improve future surveys in similar situations.

The author acknowledges the support of the Slovenian Research Agency for funding the project using questionnaires to measure attitudes and behaviours of building users (Z5-1879) and the European Commission for funding the InnoRenew project [Grant Agreement #739574] under the Horizon 2020 Widespread-Teaming program.