  How to take multiple factors into account when evaluating a Game with a
Purpose? How is player behaviour or participation influenced by different
incentives? How does player engagement impact their accuracy in solving tasks?
In this paper, we present a detailed investigation of multiple factors
affecting the evaluation of a GWAP and we show how they impact on the achieved
results. We inform our study with the experimental assessment of a GWAP
designed to solve a multinomial classification task.
