How much is it about the money? Using facebook to promote a web survey during the COVID-19 pandemic and estimating average response-returns on ad-investments

The use of ads posted on online social networks has become a popular strategy to recruit survey participants. This paper quantifies the returns from ad-investments in terms of the number of responses. We use as a case study a survey about living and working conditions that was promoted in Spain via Facebook from March 2020 to October 2021. Results show that the effect of each additional euro invested in Facebooks ads daily generated between 2 and 2.8 additional completed surveys per day. These results are stable and consistent throughout the period we study. Nonetheless, we find that the number of survey responses tended to be significantly higher when the COVID-19 restrictions imposed were tighter. Our findings are relevant and have practical implications for future survey research.