Clinical trials are prospective experimental studies conducted on humans to determine the safety and efficacy of treatments, drugs, diet methods, and medical devices. Using statistics in clinical trials enables researchers to derive reasonable and accurate conclusions from the collected data, allowing them to make wise decisions in uncertain situations. In medical research, statistical methods are crucial for preventing errors and bias.

There are four phases in a clinical trial. A phase one study establishes the basic pharmacology profile, such as absorption, distribution, metabolism, and elimination of drugs. In phase two, studies demonstrate the safety profile and efficacy of the drug. During the third phase, several hundred to several thousand patients are involved over a short period to establish the drug dose, dosage, and efficacy. As soon as the phase three trial is completed, the results are submitted to regulatory agencies such as the FDA for approval to market the drug, as long as the drug meets all the requirements and is marketed for regular use. Post-marketing surveillance is the fourth phase of clinical trials. Researchers examine the drug's therapeutic potential in diverse populations with various clinical conditions and taking multiple medications.