Smartphone apps are increasingly being used for population-based survey research. Recruiting people to sign up for an app-based survey is, however, less straightforward compared to traditional surveys, which risks inflating nonresponse as well as the potential for nonresponse bias. By means of an experiment with over 44,000 recently registered job seekers, we present causal evidence on the effects of using different contact modes (email, postal letter, or preannouncement letter and email) on participation rates in an app-based panel survey. Further, using detailed administrative register data, we investigate whether contact modes differentially affect nonresponse bias. We also examine whether the mode of making contact has a lasting effect on panel participation rates and participation rates in momentary assessments collected using the experience sampling method (ESM). Overall, the preannouncement letter and email invitation strategy maximizes participation compared to stand-alone letters and emails, which do not differ significantly in terms of participation rates. Stand-alone letters and the preannouncement approach perform better than emails when it comes to panel participation and submitted ESM episodes.

智能手机应用程序越来越多地用于基于人口的调查研究。但是，与传统调查相比，招募人员注册进行基于应用程序的调查要简单得多，因为传统调查可能会增加无应答的可能性以及无应答偏见的可能性。通过对超过44,000名最近注册的求职者进行的实验，我们提供了因果关系的证据，说明了基于应用程序的小组调查中使用不同的联系方式（电子邮件，邮政信或预先公告信和电子邮件）对参与率的影响。此外，通过使用详细的行政登记数据，我们研究了联系方式是否有差异地影响无响应偏差。我们还检查了联系方式是否对专家组的参与率和使用经验抽样方法（ESM）收集的瞬时评估中的参与率具有持久影响。总体而言，与独立信件和电子邮件相比，预公告信件和电子邮件邀请策略可以最大程度地提高参与度，而独立信件和电子邮件的参与率没有明显差异。当涉及小组讨论和提交ESM情节时，独立信件和预告方法的性能要优于电子邮件。