The Purchasing Managers Index (PMI) is calculated using survey data collected from purchasing managers in various industries. The survey typically asks respondents about key aspects of their business activity, such as new orders, production levels, employment, supplier deliveries, and inventories. The PMI is calculated as a weighted average of these sub-indices, with a focus on new orders and production.

The significance of the PMI's numerical value lies in its ability to provide a snapshot of the economic health of the manufacturing or services sector. A reading above 50 indicates expansion in the sector, implying that economic activity is increasing. Conversely, a reading below 50 suggests contraction, indicating a slowdown in economic activity. The PMI provides valuable insights into the direction and pace of economic growth, offering early indications of potential changes in business conditions.

Moreover, the PMI's numerical value can help identify trends and turning points in the economy. A consistently high PMI value suggests a robust and growing economy, while a consistently low PMI value may indicate a sluggish or contracting economy. The PMI's significance lies in its ability to guide policymakers, investors, and businesses in making informed decisions based on the prevailing economic conditions.