Previously, linear trends were revealed in the differences between the headline CPI and the price indices for various subcategories of the CPI in the United States. These trends can be continuous, as observed with the price index for medical care, or piecewise with turning points between trends with opposite signs. Similar features are found for the PPI and its components. The presence of sustainable trends in the differences allows prediction of prices for various commodities at time horizons of several years. In addition, it is possible to time the start of transition to the next trend. Accordingly, the trends reduce the uncertainty in forecasting prices for major commodities and also for their small components. The usage of trends in the PPI could bring substantial benefits to producers (planning) and stock market participants (timely investment).
