You are trying to decide whether to take a vacation. Most of the costs of the vacation (airfare, hotel, and forgone wages) are measured in dollars, but the benefits of are psychological. How can you compare the benefits to the costs in deciding whether going on vacation is worth it?

The correct answer is to put the two variables in the same type of measure.  

Explanation:

To begin with, in order to compare to different variables that are in different measures the correct way to proceed is to put them in the same measure so therefore they will be comparable with each other. Once said that, in this case the person should put the psychological benefits in economics benefits as it is the other variable and in order to do that the person should think of what aspects of his productivity would increase if he takes the vacations and gains the psychological benefits. For example, after getting back from the holidays he may feel himself less stress and more relax and therefore that he may be able to either do more job, more studies or more excercises and all that can impact in an economic way.