Final answer:
A double-blind experiment is the experimental design that reduces experimenter bias. In this design, both the participants and the researchers are blinded to group membership, preventing bias in the experiment. It is considered the gold standard for clinical trials.
Step-by-step explanation:
The experimental design that reduces experimenter bias is a double-blind experiment. In a double-blind experiment, both the participants and the researchers involved with the participants are blinded. Blinding refers to the practice of hiding information about which participants are receiving the active treatment and which are receiving the placebo treatment. This helps prevent bias in the experiment and is considered the gold standard for clinical trials of vaccines, therapeutic drugs, and other medical treatments.