single-blind vs. double-blind

of or relating to an experiment or clinical trial in which the researchers but not the subjects know which subjects are receiving the active medication or treatment and which are not: a technique for eliminating subjective bias, as the placebo effect, from the test results.

of or relating to an experiment or clinical trial in which neither the subjects nor the researchers know which subjects are receiving the active medication, treatment, etc., and which are not: a technique for eliminating subjective bias from the test results.