What does “supported by evidence” mean?
Why does the research question of a study matter?
Research may examine benefits, unwanted effects or experiences. The appropriate design depends on the question. A survey and a treatment comparison provide different kinds of answers. [1]
General information for adults. Not medical or psychotherapeutic advice; not a substitute for examination, diagnosis or treatment.
Sources & editorial status
- IQWiG: Types of studies (German-language source) ↗
Methods explainer on research questions, comparison groups and random allocation. Accessed: 29 October 2026.
Compiled from an existing article: 31 October 2026. Source comparison in the article: 29 October 2026. Prepared with AI assistance; independent medical review is pending. Editorial compilation; independent medical expert review has not taken place.
Editorial responsibility: Mario V.W.B.R. Obst. Known limitations and the use of each source are explained alongside the reference. A source-comparison date is not the publication date of the original source.