The controlled experiment is highly regarded because its properties permit conclusions with the most scientific rigor. Controlled experimentation is important for the foundation of disciplines that claim to be scientific. It is also important to conduct them properly: they come at a high cost in time, effort and participation; there is an esteem that confers credibility; there is an ethical responsibility to human subjects. However, the quality of controlled experiments performed in health informatics and computer science is often poor; evidence shows that informatics and computing...