# Is it just convention to write “dependent expression/independent expression” or there is any particular reason?

elastic modulus : stress/strain. why it could not be strain / stress? My answer is the amount of stress depends on the amount of strain. So we must write stress is proportional to strain and the modulus will be stress/strain. Is my answer correct? If it is then is it just a convention to write relations like this or it has a particular reason?

• Convention. $A \propto B$ and $B \propto A$ mean the same thing, it depends on us where we put the proportionality constant and define that constant thereafter. – Mitchell Jun 16 '17 at 18:31