Consumer Price Index (CPI) Measures prices of typical purchases made by consumers, based on a typical market basket of goods and services required by average consumers

A system is a group of interacting or interrelated elements that act according to a set of rules to form a unified whole. 
An 'information system' means a discrete set of information resources organized for the collection, processing, maintenance, use, sharing, dissemination, or disposition of information.

Engineering economics, previously known as engineering economy, is a subset of economics concerned with the use and "...application of economic principles" in the analysis of engineering decisions.