Purchasing managers' indexes (PMI) are economic indicators derived from monthly surveys of private sector companies. The three principal producers of PMIs are the Institute for Supply Management (ISM), which originated the manufacturing and non-manufacturing metrics produced for the United States, the Singapore Institute of Purchasing and Materials Management (SIPMM), which produces the Singapore PMI, and the S&P Global (from 2022 merger with IHS Markit), which produces metrics based on ISM's work for over 30 countries worldwide. ISM, SIPMM, and S&P separately compile purchasing managers' index (PMI) surveys on a monthly basis by polling businesses which represent the makeup of the respective business sector. ISM's surveys cover all NAICS categories. SIPMM survey covers all manufacturing sectors. The S&P survey covers private sector companies, but not the public sector. ISM began to produce the report for the United States in 1948. The surveys are released shortly after the end of the reference period. The actual release dates depend on the sector covered by the survey. Manufacturing data are generally released on the first business day of the month, followed by construction (S&P only) on the second working day, and non-manufacturing/services on the third business day. SIPMM produces the monthly bulletin since 1998 for the Singapore manufacturing sectors, with a focus on the electronics manufacturing sector since 1998. The data are released on the second business day of each month. The Chicago-PMI survey, owned by Deutsche Börse, registers manufacturing and non-manufacturing activity in the Chicago Region. Investors value this indicator because the Chicago region somewhat mirrors the United States overall in its distribution of manufacturing and non-manufacturing activity. In 2002, SIPMM assisted China Federation of Logistics and Purchasing (CFLP) to produce the China Official PMI. ISM, SIPMM and Markit purchasing managers indices include additional sub indices for manufacturing surveys such as new orders, employment, exports, stocks of raw materials and finished goods, prices of inputs and finished goods. Formula, calculation, and reading PMI data are presented in the form of a diffusion index, which is calculated as follows where: P1 = Percentage number of answers that reported an improvement. P2 = Percentage number of answers that reported no change. P3 = Percentage number of answers that reported a deterioration. Because of P1 + P2 + P3 = 100, Thus, if 100% of the panel reported an improvement, the index would be 100.0. If 100% reported a deterioration, the index would be zero. If