Unreliable numbers: error and harm induced by bad design can be reduced by better design

Number entry is a ubiquitous activity and is often performed in safety- and mission-critical procedures, such as healthcare, science, finance, aviation and in many other areas. We show that Monte Carlo methods can quickly and easily compare the reliability of different number entry systems. A surprising finding is that many common, widely used systems are defective, and induce unnecessary human error. We show that Monte Carlo methods enable designers to explore the implications of normal and unexpected operator behaviour, and to design systems to be more resilient to use error. We demonstrate novel designs with improved resilience, implying that the common problems identified and the errors they induce are avoidable

Safer User Interfaces: A Case Study in Improving Number Entry

Numbers are used in critical applications, including finance, healthcare, aviation, and of course in every aspect of computing. User interfaces for number entry in many devices (calculators, spreadsheets, infusion pumps, mobile phones, etc.) have bugs and design defects that induce unnecessary use errors that compromise their dependability. Focusing on Arabic key interfaces, which use digit keys 0-9-· usually augmented with correction keys, this paper introduces a method for formalising and managing design problems. Since number entry and devices such as calculators have been the subject of extensive user interface research since at least the 1980s, the diverse design defects uncovered imply that user evaluation methodologies are insufficient for critical applications. Likewise, formal methods are not being applied effectively. User interfaces are not trivial and more attention should be paid to their correct design and implementation. The paper includes many recommendations for designing safer number entry user interfaces

From premature semantics to mature interaction programming

As HCI has progressed as a discipline, perhaps just as time has passed, the engineering work of programming has become increasingly separated from the HCI, the core user interface design work. At the same time, the sophistication of digital devices, across multiple dimensions, has grown exponentially. The result is that HCI and User Experience (UX) professionals and programmers now work in very different worlds. This separation causes problems for users: the UX is attractive but the program is unreliable, or the program is reliable but unattractive or unhelpful to use, correctly implementing the wrong thing. In this chapter, we dig down from this high-level view to get to what we identify as a new sort of fundamental problem, one we call premature semantics. Premature semantics must be recognised and understood by name by UX and HCI practitioners and addressed by programmers

Structural usability techniques for dependable HCI.

Since their invention in the middle of the twentieth century, interactive computerised systems have become more and more common to the point of ubiquity. While formal techniques have developed as tools for understanding and proving things about the behaviour of computerised systems, those that involve interaction with human users present some particular challenges which are less well addressed by traditional formal methods. There is an under-explored space where interaction and the high assurances provided by formal approaches meet. This thesis presents two techniques which fit into this space, and which can be used to automatically build and analyse formal models of the interaction behaviour of existing systems. Model discovery is a technique for building a state space-based formal model of the interaction behaviour of a running system. The approach systematically and exhaustively simulates the actions of a user of the system; this is a dynamic analysis technique which requires tight integration with the running system and (in practice) its codebase but which, when set up, can proceed entirely automatically. Theorem discovery is a technique for analysing a state space-based formal model of the interaction behaviour of a system, looking for strings of user actions that have equivalent effects across all states of the system. The approach systematically computes and compares the effects of ever-longer strings of actions, though insights can also arise from strings that are almost equivalent, and also from considering the meaning of sets of such equivalences. The thesis introduces and exemplifies each technique, considers how they may be used together, and demonstrates their utility and novelty, with case studies

A novel pen-based calculator and its evaluation

A novel calculator, ideal for interactive whiteboards and pen-based devices, is introduced and evaluated. The calculator provides a natural, dynamic method of entering conventional expressions by handwriting and provides continual feedback showing the calculation and results. The user interface adjusts and copes with partial expressions, morphing the expressions to correct position and syntax. Gestures are also used to edit and manipulate calculations. The user interface is declarative, in that all displays, even with partial user input, are of correct calculations. The new calculator is faster for more complex expressions and importantly, gives users more confidence in its use. The majority of users said that they would prefer to use this calculator rather than their conventional calculator. Author Keywords Handheld calculators, gesture input, novel interfaces