Utility Theory:
Utility theory is a concept in economics that aims to quantify the satisfaction or happiness that individuals derive from consuming goods and services. It assumes that individuals make decisions based on maximizing their own utility or well-being. Utility theory is widely used in economic analysis to study consumer behavior and make predictions about their choices.

Cardinal Measure of Utility:
The cardinal measure of utility refers to a numerical representation of the amount of utility an individual derives from consuming a good or service. It assigns a specific numerical value to the level of satisfaction or happiness associated with each consumption choice.

Explanation:
The cardinal measure of utility is required in utility theory. This is because utility theory assumes that individuals can assign numerical values to the satisfaction or happiness they derive from consuming different goods and services. These numerical values, or utility scores, allow economists to analyze and compare consumer preferences and make predictions about their choices.

In utility theory, the concept of utility is subjective and varies from individual to individual. It is not directly observable and cannot be measured in absolute terms. However, by using a cardinal measure of utility, economists can compare the relative level of satisfaction or happiness associated with different consumption choices.

The cardinal measure of utility allows economists to construct utility functions, which represent the relationship between the consumption of goods and services and the level of utility derived from them. These utility functions can be used to analyze consumer behavior, predict choices, and study the effects of changes in prices or income on consumer welfare.

Conclusion:
In conclusion, the cardinal measure of utility is required in utility theory to quantify the satisfaction or happiness individuals derive from consuming goods and services. It allows economists to analyze and compare consumer preferences, predict choices, and study the effects of changes in prices or income on consumer welfare.