Some have promoted particular types of evidence as 'best' for policymakers to consider, including scientifically rigorous evaluation studies such as randomized controlled trials to identify programs and practices capable of improving policy-relevant outcomes. However, some areas of policy-relevant knowledge are not well served by quantitative research, leading to debate about the methods and instruments that are considered critical for the collection of relevant evidence. For instance, policies that are concerned with human rights, public acceptability, or social justice may require other evidence than what randomized trials provide, or may require moral philosophical reasoning in addition to considerations of evidence of intervention effect (which randomised trials are principally designed to provide). Good data, analytical skills and political support to the use of scientific information, as such, are typically seen as the important elements of an evidence-based approach.