A double-blind study is a research method used to test the effectiveness of a treatment or intervention. In this type of study, neither the participants nor the researchers know who is receiving the treatment and who is receiving a placebo. This helps to eliminate bias, ensuring that the results are based solely on the treatment's effects rather than expectations or opinions. By keeping both parties in the dark, a double-blind study provides more reliable data. This method is commonly used in clinical trials for new medications, where the goal is to determine if a drug, like aspirin, truly works better than a sugar pill.