Samuel Bostaph wrote:  
>  The implicit cost of such relations is,  
> of course, what a man would have to pay a prostitute for those same  
> services.  
  
  
The GDP, of course, measures value added. Sex, at least in the form    
discussed here, involves two people each of whom has an imputed input    
cost paid to the other. The value added by the transaction is zero.  
  
Ken Gordon