What you eat is how many you are

摘要

How do people make decisions? A standard answer (not the only one) runs as follows: every individual first ranks all alternatives open to them, and then chooses the top of the list. This model had not been validated by econometric studies, but now a simple realization has changed the situation: two people don't act the same way as one. This picture of decision-making can very easily be cast into a mathematical model. IfK is the set of possible decisions, the ranking is defined by the 'utility function', U(K). The individual prefers one decision over another if the value of its utility function is higher. Taking the right decision then amounts to finding in the set K the point x that yields the greatest utility U(x). In this way, every problem in decision-making can be translated into a mathematical problem.