Mobile Apps pose a unique set of challenges for marketers and developers. On the web, you can iterate on content and features in near-real-time and deploy conversion tracking, Remarketing, analytics and other tags to measure the effects on your users. Apps, on the other hand, are effectively frozen at the point of user install. Making even the slightest change means waiting until your next update makes its way through the various app stores and even then, you can’t be sure that all of your users will update quickly, if at all.
Read more at Google Analytic Blog