How to Calculate Comparative Advantage?

You can ascertain which economic agent has comparative advantage by looking at the opportunity cost ratio. Opportunity Cost Ratio is simply the ratio of number of units of a good to be given up in order to produce an additional unit of another good. The economic agent with the lower opportunity cost ratio is the one who has the comparative advantage.
We once again take a look at the same example as above. Person A has to give up 1.67 units of good Y in order to produce one more unit of good X whereas person B has to give up only 1.5 units of good Y to produce one more unit of good X. Opportunity cost ratio for person A is 1.67 and that for person B is 1.5. Therefore, person B has the comparative advantage in production of good X because he has a lower opportunity cost ratio.