Body mass index (BMI) is a commonly used international index to measure obesity and health. The normal body mass index is between 20 and 25. If it exceeds 25, it means overweight, and if it exceeds 30, it means obesity.
Extended data index, or statistical index, is an important statistical method to analyze the quantitative changes of social and economic phenomena. It came into being in the second half of18th century. At that time, due to the continuous inflow of gold and silver mined in the New World of America into Europe, the prices in Europe suddenly rose, which aroused widespread concern in society. In order to measure price changes, economists began to try to compile price indexes.