View the model
Download the model
The Power utility function provides a flexible way of specifying your risk tolerance.
If wealth( s) is your wealth outcome under scenario s,
the Power utility function is: Utility( wealth(s)) = (wealth(s)^gamma -1)/gamma.
where 0 <= gamma
gamma = 1 means risk neutral, i.e. utility is linear in end of period wealth.
gamma < 1 means risk averse, and
gamma > 1 means risk preferring.
Using L'hopital's rule, you can show that as gamma approaches 0,
the power utility function value approaches log( w), where log( ) is the natural logarithm.
Log Utility
The Log utility function is a special case of the Power utility, corresponding to the case gamma = 0.
utility( wealth(s)) = log( wealth( s)).
In this case, rather than using the power utility with gamma = 0, one should use the Log utility explicitly.