Domain-specific participant recruitment exceeds the application of "Targeted" advertisement from common online advertising platforms.

INTRODUCTION

Insufficient sample sizes threatened the fidelity of the primary research trials. Even if the research group recruits a sufficient sample size, the sample may lack diversity, reducing the generalizability of the results of the study. Evaluating the effectiveness of online advertising platforms (e.g., Facebook & Google Ads) versus traditional recruitment methods (e.g., flyers, clinical participation) is essential.

METHODS

Patients were recruited through email, electronic direct message, paper advertisements, and word-of-mouth advertisement (traditional) or through Google Ads and Facebook Ads (advertising) for a longitudinal study on monitoring COVID-19 using wearable devices. Participants were asked to wear a smart watch-like wearable device for ∼ 24 hours per day and complete daily surveys.

RESULTS

The initiation conversion rate (ICR, impressions to pre-screen ratio) was better for traditional recruitment (24.14) than for Google Ads, 28.47 ([0.80, 0.88]; p << 0.001). The consent conversion rate (CCR, impressions to consent ratio) was also higher for traditional recruitment (66.54) than for Google Ads, 2961.20 ([0.015, 0.030]; p << 0.001). Participants recruited through recommendations or by paper flier were more likely to participate initially (Χ = 23.65; p < 0.005). Clinical recruitment led to more self-reporting white participants, while other methods yielded great diversity (Χ = 231.47; p << 0.001).

CONCLUSIONS

While Google Ads target users based on keywords, they do not necessarily improve participation. However, our findings are based on a single study with specific recruitment strategies and participant demographics. Further research is needed to assess the generalizability of these findings across different study designs and populations.