The mobilization effect of social media use: an instrumental variable approach

Abstract

Social media has been considered to facilitate more online political participation (OPP) due to being less bounded by time and space constraints. However, in the context of normalization theory, social media use (SMU) might merely reflect the status quo, not facilitating additional engagement. Although extant studies on ‘who participates online’ raise the question of the critical factors of OPP, these studies only consider whether contacts between individuals have increased. Furthermore, according to mobilization theory, the effect of networks composed by SMU on OPP was empirically vague. Whether mobilization results in increased or decreased OPP may vary depending on the characteristics of the network. We exploit an instrumental variable to address these limitations and lacunas. The reasons are as follows: Firstly, without using an instrumental variable, adequately verifying the mobilization hypothesis is challenging due to reverse causality and contrasting expectations derived from normalization theory. Secondly, while the coefficient’s sign is crucial for measuring the effects of homophily and heterophily, not using instrumental variables risks underestimating these effects. In conclusion, the models that employ the instrumental variable demonstrate a considerably larger effect size compared to others. Therefore, it appears that greater SMU correlates with increased OPP, supporting the theoretical claims that social media can promote participation and the mobilization hypothesis.