Opportunity cost like other basic concepts of Economics – scarcity, scale of preference and choice is important to an individual who represents the consumer or household, or firm or productive unit and the government that form the three decision making bodies in an economy.
A scale of preference can be defined as the list of a person's needs or wants written in an order of importance. You will observe that the person puts his most important needs or wants at the top of the list.
A scale of preference is a list of goods and services (for example, shoes, socks, books, haircut, and so on) prepared for purchase in order of priority. It is a priority rating of all individual wants, according to their importance in one's valuation and the means to achieve or obtain them.