In a single blind experiment, the subjects don’t know if they are the experiment test group or members of the control group but the tester knows. The subjects are not told their identities in the experiment. The subject receiving the medicine would not know if they were receiving the drug or the placebo. In the double blind experiment, both the tester and the subjects are blinded. Both the tester and the subject doesn’t know the identities in the experiment. Neither the patients receiving the treatment nor the doctor distributing the medicine would know if the patients were receiving the drug or the placebo. Since the tester does not know which group received the placebo or the experimental drug means that the risk of conscious and unconscious observer bias is reduced, making the study more accurate. Usually researchers go with randomized single blind and double blind experiment setup to prevent any type of bias in the results.