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So far, most Phase II trials have been designed and analysed under a frequentist framework. Under this framework, a trial is designed so that the overall Type I and Type II errors of the trial are controlled at some desired levels. Recently, a number of articles have advocated the use of Bayesian designs in practice. Under a Bayesian framework, a trial is designed so that the trial stops when the posterior probability of treatment is within certain prespecified thresholds. In this article, we argue that trials under a Bayesian framework can also be designed to control frequentist error rates. We introduce a Bayesian version of Simon's well-known two-stage design to achieve this goal. We also consider two other errors, which are called Bayesian errors in this article because of their similarities to posterior probabilities. We show that our method can also control these Bayesian-type errors. We compare our method with other recent Bayesian designs in a numerical study and discuss implications of different designs on error rates. An example of a clinical trial for patients with nasopharyngeal carcinoma is used to illustrate differences of the different designs.

PurposeInspired by the dynamic changes in our daily lives enabled via quantified-self technologies and the urgent need for more studies on the human-computer interaction design mechanisms adopted by these applications, this study explores the value of user affective experience mirroring and examines the empowerment effect of meaningful gamification in a psychological self-help system (PSS) that aids people in work stress relief.Design/methodology/approachBased on an analysis of the existing systems and theories in relevant fields, we conducted mixed-method research, involving semi-structured interviews, experience sampling experiments and user bio data triangulations, to identify the benefits of user affective experience mirroring and examine the impact of visual impact metaphor–based (VIM) meaningful gamification on PSS users.FindingsFor a gamified PSS, users generally perceive VIM as arousing more feelings of enjoyment, empathy, trust and usefulness, empowering them to gain more mastery and control over their emotional well-beings, especially with relieving their occupational stress and upbringing their level of perceived happiness. Overtime, VIM-based meaningful gamification further boosts such value of a PSS.Research limitations/implicationsWeaving together meaningful gamification and psychological empowerment theories, the results emphasized that successful empowerment of user through gamification in PSSs relies heavily on whether a deeper and meaningful affective connection can be established with the users, in short, “meaningful gamification for psychological empowerment”. Such an understanding, as demonstrated in our research framework, also sheds light on the design theories for persuasive technology and human influence tactics during human computer interactions.Practical implicationsThe results of the study demonstrate to practitioners how to make the best use of gamification strategies to deeply relate to and resonate with users. Even without complicated game-play design, meaningful gamification mechanisms, such as VIM facilitate the empowerment of users while gaining their appreciation, establishing a deeper connection with them and eventually generating persuasive effects on intended future behavioural outcomes.Social implicationsThe effective management of work-related stress with handy tools such as a VIM-based PSS can be beneficial for many organizations and, to a large extent, the society.Originality/valueThis study proposed and empirically demonstrated the empowerment effect of meaningful gamification for PSS users. In this cross-disciplinary study, theories from different research domains were synthesized to develop a more thorough and multi-faceted understanding of the optimal design strategies for emerging information systems like this VIM-based PSS.

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