Advantages: contingency table is a frequency table formed when observation samples are classified by two or more attributes (qualitative variables). It is a table that is often used to sort out and express counting data, and is widely used in medical scientific research activities. In medical research papers, the basic problem to be solved in statistical analysis of contingency table is to determine whether there is correlation between the investigated attributes, that is, whether they are independent. There are many statistical analysis methods for contingency table analysis, including chi-square test, rank sum test, Ridit analysis, correspondence analysis, rank correlation analysis, linear trend test and consistency test. Disadvantages: Too much data is easy to make mistakes.