Final answer:
The Utility Index by Von Neumann and Morgenstern measures utility where risk is present, aids in preference-based decision-making, and is used for predictions, although it deals with the unquantifiable unit of utils which are subjective and not comparable between individuals.
Step-by-step explanation:
The Utility Index, proposed by Von Neumann and Morgenstern, is a concept in economics that involves measuring utility in situations where risk exists. It enables decision-making based on preferences and is often used for predictive purposes. This index provides a way to quantify satisfaction or happiness from consuming goods and services. For instance, when making consumption decisions, individuals consider various factors to achieve the highest level of utility or satisfaction. Even though we cannot measure utils, which are theoretical units of utility, this concept helps us understand consumer choices.
The idea of utils being subjective and not directly comparable between individuals is central to the notion of utility. This leads us to the law of diminishing marginal utility, which states that the utility gained from consuming additional quantities of a good decreases after a certain point. While utils are difficult to quantify, the Utility Index helps in transforming these subjective measures into more quantifiable terms like demand.