The reason why interim analysis is widely used is the soaring cost of clinical research and significant trial failures. In clinical trials and other scientific studies, interim analyses are often performed before the completion of the trial, and the intention of this analysis is to determine whether the trial is terminated prematurely or to adjust the sample size. Interim analysis of clinical trials keeps the decision process free of conflict of interest while considering cost, resources, and meaningfulness of the project. This reasonable approach helps to analyze and predict the results of clinical trials. If necessary, such an interim analysis can also call for early termination or appropriate modification of the sample size, study design, or even early declaration of success.