- Specifically, we suggested that scientific rigor meant that the research should be theoretically grounded or based on informed notions about the nature of phenomena, and of the relationships between events, factors and variables.

- It also implies a sound research design including appropriate sampling, data collection, processing and analysis procedures as well as ethical considerations such as the protection of confidentiality and obtaining informed consent.

- Our WHO Working Group would endorse these criteria, but also suggest that there are a number of other principles that we should take into consideration in the evaluation of health promotion initiatives.