We can draw a correct conclusion unless we select appropriate measurement parameters and properly do the statistical analysis including description and inference, after checking and processing the data of therapeutic study. A comprehensive understanding and correct application of the measurement parameters as well as statistical processing is the key to improve our scientific research. In this article, some common mistakes were addressed in the light of basic concepts in therapeutic study, focusing on the measurement parameters (survival rate, negative conversion rate or positive conversion rate, relative benefit increase, relative risk reduction, relative risk increase, number needed to treat, likelihood of being helped vs. harmed, index of effectiveness) and statistical processing (data type, distribution character, intention-to-treat analysis, efficacy analysis, treatment received analysis, hypothesis testing).