Where can I find an explanation of why Republican delegate numbers are always larger than Democratic delegates

at caucuses? I know it has to do with the DNC not publisizing the actual number of caucus goers as the RNC does and instead only publishes the country delegates earned. It was explained on CNN during the Iowa caucuses, but I don't know where to look to find it written down. I'm trying make Ron Paul supporters understand that he didn't get more votes than Clinton, or that Romney got more votes than all the democratic candidates combined even though there were more democratic voters than republicans in the caucus. (Yes, it should seem like common sense, but these are Ron Paul supporters and are surprisingly immune to logic)