Market Definition in the Attention Economy: An Experimental Approach

I study demand for popular mobile phone applications by conducting an experiment where I monitor how participants spend time on digital services and shut off access to Instagram or YouTube on their Android phones. I characterize how participants substitute their time during the restrictions by estimating the magnitude of across product category and off phone substitution as well as computing diversion ratios between prominent social media applications. I relate the estimates to ongoing debates about relevant market definition for social media applications and conclude that they may be larger than those considered by regulatory authorities and smaller than those posited by technology companies.