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To increase police officer awareness of incident locations, the Dutch police developed and implemented a location-based notification system (LBNS). This mobile service notifies police officers proactively to warrants, agreements and police focal points in their current vicinity. To assess the accuracy, efficiency, effectiveness and user experience of this service, a longitudinal field evaluation was conducted with thirty police officers over four months. The results show that using the LBNS, police officers were better informed of relevant information in their environment and this led to positive operational results. Users considered the interface clear and easy to use. However, users indicated that the system presented too many or non-relevant notifications and that the system is overly complex. Recommendations for further development of the LBNS are to mitigate unwanted interruption by intelligent filtering of notifications and integration of system components.

Evaluation refines and validates design solutions in order to establish adequate user experiences. For mobile user interfaces in dynamic and critical environments, user experiences can vary enormously, setting high requirements for evaluation. This chapter presents a framework for the selection, combination, and tuning of evaluation methods. It identifies seven evaluation constraints, that is, the development stage, the complexity of the design, the purpose, participants, setting, duration, and cost of evaluation, which influence the appropriateness of the method. Using a combination of methods in different settings (such as Wizard-of-Oz, game-based, and field evaluations) a concise, complete, and coherent set of user experience data can be gathered, such as performance, situation awareness, trust, and acceptance. Applying this framework to a case study on context-aware mobile interfaces for the police resulted in specific guidelines for selecting evaluation methods and succeeded to capture the mobile context and its relation to the user experience.

This paper describes a user walkthrough that was conducted with an experimental multimodal dialogue system to access a multidimensional music database using a simulated mobile device (including a technically challenging four-PHANToM-setup). The main objectives of the user walkthrough were to assess user preferences for certain modalities (speech, graphical and haptictactile) to access and present certain types of information, and for certain search strategies when searching and browsing a multidimensional database. In addition, the project aimed at providing concrete recommendations for the experimental setup, multimodal user interface design and evaluation. The results show that recommendations can be formulated both on the use of modalities and search strategies, and on the experimental setup as a whole, including the user interface. In short, it is found that haptically enhanced buttons are preferred for navigating or selecting and speech is preferred for searching the database for an album or artist. A 'direct' search strategy indicating an album, artist or genre is favorable. It can be concluded that participants were able to look beyond the experimental setup and see the potential of the envisioned mobile device and its modalities. Therefore it was possible to formulate recommendations for future multimodal dialogue systems for multidimensional database access.

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