The is a method in which neither the research participants nor the researchers know whether the participants are getting the treatment or a placebo.

The double-blind study is a method in which neither the research participants nor the researchers know whether the participants are getting the treatment or a placebo. Is a tool of the scientific method used to prevent research results can be influenced by the placebo effect or observer bias.

the historians cited in the article all agree with one another about the cause of the civil war. despite coming from different backgrounds and cultures, the historians agree that slavery was the root cause of the civil war. the fact that all these historiansgenerally agree with one another makes their shared viewpoints more reliable and valid, especially because the historians have different backgrounds and all work for the well-respected institutions of howard university, clemson university, and the university of colorado.