1 Line of Code = $1.00??

What's the best way for a non-coder to determine the efficiency of their contracted programmer. I've been developing a SaaS product for the last 4 months which is my first project that is being programmed from the ground up. I am a business owner and have hired designers in the past to put together informational sites. I myself have customized and implemented eCommerce sites within ecommerce platforms such as magento, volusion, channel advisor, but of course that's completely different as you're working within a pre-created platform. This is my first time putting together something that requires programming from the ground up.I started off by putting together a descriptive Axure wireframe. I learned Axure very quickly and within a months time I was half way done with my wireframe and knowledgeable in all of Axures features and functions. (my friend, a senior UX/UI guy at a big firm said I'm almost as good as he is) haha. I made it a point to be very descriptive with my wireframe notes as well as building the wireframe as close as I could to the real thing. Any programmer should have the ability to spend no more than 30 minutes on the functional wireframe and get the point of the entire platform and how it all ties in together. I designed the wireframe for both the web designer and programmer so it almost looks and functions as I would want it to once finished and thus far it has been on point. So based on how I've handled things on my end, how could I determine that a programmer is efficiently working and not wasting time?I've hired them through odesk so I do get to see screen shots. I am using a repository (github) so I do have access to fresh code every week. The language it's being built on is Python with jquery framework. The developer is considered to be a senior and I'm paying a little over $20 per hour. Also, this is a general question, no so much based on my situation. Just want to figure out helpful ways for a non-programmer to better manage a project.