Short-format videos have exploded on platforms like TikTok, Instagram, and YouTube. Despite this, the research community lacks large-scale empirical studies into how people engage with short-format videos and the role of recommendation systems that offer endless streams of such content. In this work, we analyze user engagement on TikTok using data we collect via a data donation system that allows TikTok users to donate their data. We recruited 347 TikTok users and collected 9.2M TikTok video recommendations they received. By analyzing user engagement, we find that the average daily usage time increases over the users' lifetime while the user attention remains stable at around 45%. We also find that users like more videos uploaded by people they follow than those recommended by people they do not follow. Our study offers valuable insights into how users engage with short-format videos on TikTok and lessons learned from designing a data donation system.

翻译：短视频在TikTok、Instagram和YouTube等平台迅速崛起。然而，学术界仍缺乏关于人们如何参与短视频以及提供无尽内容流的推荐系统作用的大规模实证研究。本研究借助数据捐赠系统收集数据，允许TikTok用户捐赠其数据，从而分析用户参与情况。我们招募了347名TikTok用户，收集了他们收到的920万条TikTok视频推荐。通过分析用户参与，我们发现用户日均使用时长随使用时间推移而增加，而注意力保持率稳定在45%左右。此外，用户更倾向于点赞其关注者上传的视频，而非推荐者未关注用户的视频。本研究为理解用户在TikTok上参与短视频的行为提供了宝贵见解，并总结了设计数据捐赠系统的经验教训。