OpenSignal: Size matters
With 9,962 Android devices used for the survey, OpenSignal found a positive correlation between display size and data usage over Wi-Fi. This correlation also shows up between display size and data usage over cellular although the connection is not nearly as strong. What is interesting is that when on the go, most people use Android devices with large screens the same way they use Android devices with smaller displays. That changes when at home or at places with free Wi-Fi. That makes sense since at home, and at most places offering free Wi-Fi, there are alternative screens for viewing entertainment. On the other hand,while on the run, you have no choice but to use the screen on your phone no matter how small it is.
The study concludes that with smartphone screens increasing in size every year, data use is going to follow. And in general, when using Wi-Fi, screen-size plays a big role in determining the amount of data consumed. And while using cellular data, the amount of data used depends on factors other than screen size.
source: OpenSignal via FierceWireless