In the United States, there exist robust linear trends in the differences between headline (or core) CPI and price indices for individual subcategories of goods and services such as energy, food, housing, etc. Chiefly these differences can be represented by a piece-wise straight line. The...

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...