The ISM index is important by the American Association for supply management.

The ISM index is divided into two indexes: manufacturing index and non manufacturing index.

ISM Supply Management Association manufacturing index consists of a series of sub index, among which purchasing managers index is the most representative.

The index is a barometer reflecting the comprehensive development of manufacturing industry in terms of production, orders, prices, employees, delivery and so on. It usually takes 50 as the critical point, which is higher than 50. It is considered that the manufacturing industry is in an expansion state, and less than 50 means that the manufacturing industry shrinks and affects the pace of economic growth.

The ISM Supply Management Association's non manufacturing index reflects the prosperity of the non manufacturing business activities in the United States. When its numerical value is above 50, it indicates that the expansion of non manufacturing activities and the rising prices often indicate that the overall economy is expanding. When the value is at a level below 50, it often indicates that the overall economy is in a state of contraction.