describes the prices of raw materials for production, so it can be used to measure the price changes of various commodities at different production stages. Countries collect quotations of various commodities from major producers through statistical offices, and then calculate the percentages by their own calculation methods for comparison. At present, the data published in the United States is calculated by taking the 1967 index as 1. This index is published by the Ministry of Labor once a month. Everyone sees that if the published index is higher than expected, it means that there is a possibility of inflation. Relevant parties will study this and consider whether to implement a tight monetary policy. In this way, the currency of this country will often appreciate and produce benefits. If the index is worse than expected, then the currency will fall.