Time and sample quality in a Facebook ad-generated survey with Polish migrants in the UK

Migrants are considered a hard-to-reach population – it is hard to recruit them due to lack of accessible sampling frames or recruit in a timely manner if frames are available or self-constructed. Recently, social media advertisement campaigns (ads) have become an increasingly popular method of recruiting hard-to-reach populations, including migrants, due to lower costs and time efficiency. In this paper we concentrate on the time element of some online survey fieldwork where recruitment was facilitated with targeted Facebook ads. The paper uses data from a survey conducted for a project on the impacts of Covid-19 on Polish migrant essential workers in the UK. Over a period of four weeks in 2021, we collected 1,105 valid responses and 66% of them (735) came from a dedicated Facebook ad campaign. We review the campaign performance over time and explore different time indicators – fieldwork day, sampling stage and sampling stage day – and whether they are associated with survey response quality, satisficing and estimations. The results indicate that less-cooperative respondents are recruited later in the fieldwork, but also that the sampling stage day correlates with respondents’ engagement.