A placebo is used in clinical trials as a control in drug studies to test the effectiveness of treatments. In drug trials, one group of participants receives the medicines (to be tested), and the other gets the placebo (say, sugar pills).
The concept of placebo stems from the assumption that a treatment has two components, one related to the specific effects of the treatment and the other, nonspecific, related to its perception. When the nonspecific effects are beneficial to the participant, it is called a placebo, and when they are harmful, it is a nocebo.
Hypothesis Testing
The null hypothesis (H0) typically represents the default state or the state of “no effect“. For example, you compare the means of two groups, such as people who took a particular drug and people who received the placebo. As a drug researcher, your objective is to find the effectiveness of the medicine. And that lays the foundation for your alternative hypothesis (HA or H1) – that the drug has a non-zero effect. The default state (H0) assumes the drug has no impact. To be specific, H0 assumes the difference between two means equals zero.
