Types of evidence
We grade the references we cite in our advice pages according to the type of evidence they provide. For example, a reference may consist of a publication which gives an author's opinion, based on their own experience of a service/technology, or the publication could be a research paper recording the outcome of a study which observed 1000 individuals' use of a service/technology. Thus there is a big difference in the type of publication. We have categorised our references into the 6 categories shown below. However, we are not suggesting certain types of evidence are better than others. A narrative / descriptive publication of a user's personal experience using a technology can be just as useful for a reader as a controlled trial stating how statistically significant the use of the technology was to a specific outcome. Individual readers may prefer different types of evidence.
Type of evidence:
Supporting evidence is based on the experience and opinion of the author(s).
Supporting evidence is based on the expert opinion of panels, committees, professional groups / associations, or consumer organisations.
Supporting evidence is based on qualitative or quantitative research study designs (not listed below) including those which are descriptive /exploratory in nature. Innovative technologies/devices are supported by consumer efficacy reviews and evaluations.
Supporting evidence is based on mixed method research designs (including randomized, controlled, cohort based, case series, case-controlled or cross sectional studies) or randomized controlled trials with small sample sizes suggesting statistically non-significant trends . The equipment / devices are rigorously tested by a substantial number of users and demonstrate consistent results when used.
Supporting evidence is based on a large, long-term randomized controlled trial that yield sufficient power to confidently answer questions such as 'What equipment is most effective'." The use of the equipment / devices is supported by user data which demonstrates measured effectiveness and benefit for users.
Supporting evidence is based on systematic reviews/meta-analyses of randomized controlled trials of smaller sample sizes that yield sufficient power to confidently answer questions such as 'What equipment is most effective'. The use of the equipment / devices is supported by user data which demonstrates measured effectiveness and benefit for users.