Metrics and evaluation of spoken dialogue systems

The ultimate goal of an evaluation framework is to determine a dialogue system’s performance, which can be defined as “the ability of a system to provide the function it has been designed for” [32]. Also important, particularly for industrial systems, is dialogue quality or usability. To measure usability, one can use subjective measures such as User Satisfaction or likelihood of future use. These subjective metrics are difficult to measure and are dependent on the context and the individual user, whose goal and values may differ from other users. This chapter will survey evaluation frameworks and discuss their advantages and disadvantages. We will examine metrics for evaluating system performance and dialogue quality. We will also discuss evaluation techniques that can be used to automatically detect problems in the dialogue, thus filtering out good dialogues and leaving poor dialogues for further evaluation and investigation [62].