Smartphones and tablets are an indispensable part of
		  modern communication and people spend considerable time
		  interacting with their devices every day. While substantial
		  research has been conducted concerning smartphone usage,
		  little is known about how tablets are used. This paper
		  studies mobile device usage characteristics like session
		  length, interaction frequency, and daily usage in locked
		  and unlocked state with respect to location context. Based
		  on logs from 1,585 Android devices (470 years of total
		  usage time), we derive and analyze 23 million usage
		  sessions. We found that devices remain locked for 60% of
		  the interactions and usage at home occurs twice as frequent
		  as at work. With an average of 58 interactions per day,
		  smartphones are used twice as often as tablets, while
		  tablet sessions are 2.5 times longer, resulting in almost
		  equal aggregated daily usage. We conclude that usage
		  session characteristics differ considerably between tablets
		  and smartphones.<br>
<br><pre>@inproceedings{Hintze_14_MobileDeviceUsage,
  author = {Hintze, Daniel and Findling, Rainhard Dieter and Scholz, Sebastian and Mayrhofer, Ren\'e},
  title = {Mobile Device Usage Characteristics: The Effect of Context
  		  and Form Factor on Locked and Unlocked Usage},
  booktitle = {Proc.\ {MoMM} 2014: 12th International Conference on
  		  Advances in Mobile Computing and Multimedia},
  year = {2014},
  pages = {105--114},
  address = {New York, NY, USA},
  month = dec,
  publisher = {ACM Press},
  booktitle_short = {Proc. {MoMM} 2014},
  day = {8--10},
  documenturl = {http://www.mayrhofer.eu.org/downloads/publications/MoMM2014-Mobile-Device-Usage.pdf},
  doi = {10.1145/2684103.2684156},
  eventurl = {http://www.iiwas.org/conferences/momm2014/},
  isbn = {978-1-4503-3008-4},
  keywords = {Daily interactions, Device unlocking, Locked usage,
  		  Session length, Smartphone, Tablet, Usage session, User
  		  context},
  location = {Kaohsiung, Taiwan},
  pubtype = {conference}
}
</pre>