Universal platform support and popularity: It is examined how cross-platform the app is with regard to the
operating system on the mobile device and how popular it is for users on the respective platform. Cross-platform apps
potentially attract a bigger target group than those that are written, e.g., for the Android only, or Apple iOS only. The
2013 market shares in worldwide smartphone sales to end users by operating system7 (currently 78.4% (i.e. 0.784) for
Android, 15.6% (i.e. 0.156) for iOS) influences the metric for this criterion. It is combined with the app’s per-platform
rating: The market share of an operating system supported by the app is multiplied by the app’s normalized customer
rating for the respective platform (normalized meaning as a percentage of the maximum 5-star score, i.e. on a scale
from 0.0 to 1.0). Finally, all such products are simply added together. This way, the more important the support