Which research design ensures that neither the researcher nor the participant knows who receives the treatment or placebo?

The double-blind technique is a research design where neither the researcher nor the participants know who is receiving the treatment and who is receiving a placebo. This method helps eliminate bias in the results by ensuring that the expectations or behaviors of both the participants and the researchers do not influence the outcome of the study.

In this design, the random assignment of participants to treatment or placebo groups helps maintain the integrity of the study, as it prevents any preconceived notions about treatment efficacy from affecting the data collection or participant responses. By keeping both parties blind to group assignments, the double-blind technique enhances the validity of the research findings and is considered a gold standard in experimental research, especially in clinical trials.

Other options, such as the single-blind technique, only keep participants unaware of their group assignment, leaving researchers with knowledge of the assignments. Random assignment refers to the process of randomly distributing participants into different groups but does not inherently include the blinding aspect. A cross-sectional study is an observational design that analyzes data from a population at a specific point in time, without involving blinding between treatment or control groups.