Today, mobile devices like smartphones and tablets have
		  become an indispensable part of people’s lives, posing
		  many new questions e.g., in terms of interaction methods,
		  but also security. In this paper, we conduct a large scale,
		  long term analysis of mobile device usage characteristics
		  like session length, interaction frequency, and daily usage
		  in locked and unlocked state with respect to location
		  context and diurnal pattern. Based on detailed logs from
		  29,279 mobile phones and tablets representing a total of
		  5,811 years of usage time, we identify and analyze 52.2
		  million usage sessions with some participants providing
		  data for more than four years. Our results show that
		  context has a highly significant effect on both frequency
		  and extent of mobile device usage, with mobile phones being
		  used twice as much at home compared to in the office.
		  Interestingly, devices are unlocked for only 46% of the
		  interactions. We found that with an average of 60
		  interactions per day, smartphones are used almost thrice as
		  often as tablet devices (23), while usage sessions on
		  tablets are three times longer, hence are used almost for
		  an equal amount of time throughout the day. We conclude
		  that usage session characteristics differ considerably
		  between tablets and smartphones. These results inform
		  future approaches to mobile interaction as well as
		  security.<br>
<br><pre>@article{Hintze_17_LargeScaleLong,
  author = {Hintze, Daniel and Hintze, Philipp and Findling, Rainhard Dieter and Mayrhofer, Ren\'e},
  title = {A Large-Scale, Long-Term Analysis of Mobile Device Usage
  		  Characteristics},
  journal = {Proc.\ ACM on Interactive, Mobile, Wearable and Ubiquitous
  		  Technologies},
  year = {2017},
  volume = {1},
  number = {2},
  month = jun,
  doi = {10.1145/3090078},
  keywords = {Daily interactions, Device unlocking, Locked usage,
  		  Session length, Smartphone, Tablet, Usage session, User
  		  context},
  url = {https://dl.acm.org/citation.cfm?id=3090078}
}
</pre>