An<unk> , or<unk><unk> , is a type of clinical<unk>  in which information is not withheld from<unk>  participants. In particular, both the researchers and participants know which treatment is being administered. This contrasts with a double-blinded<unk> , where information is withheld both from the researchers and the participants to reduce bias.<unk> s may be appropriate for comparing two similar treatments to determine which is most effective, such as a comparison of different prescription anticoagulants or possible relief from symptoms of some disorders when a placebo is given. An<unk>  may still be randomized.<unk> s may also be uncontrolled (without a placebo group), with all participants receiving the same treatment.
Open-label trial
Multiple baseline design
Natural history study
Retrospective cohort study
Placebo-controlled study
Prospective cohort study
Multicenter trial
Randomized controlled trial