\section{Conclusions}
\label{sec-conclusion}

To conclude, we have argued that our inability to estimate app value is a
critical weakness that is threatening our successes at accurately estimating
and attributing energy consumption. We have motivated the need for a value
measure by describing the multiple ways in which it would aid in the
management of energy and other resources on battery-powered smartphones.
Using an energy consumption dataset collected on \PhoneLab{} we have explored
separately several potential inputs to a value measure and determined how
they weight energy consumption. Finally, we have presented results from a
failed effort to formulate an effective value measure. While this first
attempt was unsuccessful, we hope to engage the mobile systems community in
this effort so that more sophisticated and successful value measures can be
developed.

\section*{Acknowledgments}

Students and faculty working on estimating app value are supported by NSF
awards
\href{http://www.nsf.gov/awardsearch/showAward.do?AwardNumber=1205656}{1205656}
and
\href{http://www.nsf.gov/awardsearch/showAward.do?AwardNumber=1423215}{1423215}.
The authors thank the anonymous reviewers for their feedback.