  Published studies on agile effort estimation predominantly focus on
comparisons of the accuracy of different estimation methods, while efficiency
comparisons, i.e. how much time the estimation methods consume was not in the
forefront. However, for practical use in software development, the time
required can be a very important cost factor for enterprises, especially when
the accuracy of different agile effort estimations is similar. In this study,
we thus try to advance the current standard accuracy comparison between methods
by introducing efficiency i.e. time it takes to use a method as an additional
dimension of comparison. We conduct this comparison between three agile effort
estimation methods that were not yet compared in the literature, namely
Planning Poker, Bucket System and Affinity Estimation. For the comparison, we
used eight student teams with 29 students that had to use all the effort
estimation methods during the course where they had to finish a programming
project in 3 weeks. The results indicate that after the students get used to
using the different methods the accuracy between them is not statistically
significantly different, however, the efficiency is. On average Bucket System
and Affinity Estimation methods take half as much time as Planning Poker.
