Need help conducting statistical analysis on sitcoms

I'm looking to do a study where I take a cross-section of sitcoms from across the past sixty years and studying whether there's been a notable increase in Story Arcs, Character Development, Call-Backs and Continuity Nods, and self-awareness.

Now, what I'm looking for is not an opinion on the matter, but rather how I would go about conducting such a study in the most scientific way possible. My teacher tells me that simply watching and taking notes isn't enough, there's got to be some sort of system. I'm aware that strict standards for what qualifies as a Story Arc or Character Development and so forth need to be established, but outside of that I'm lost. A lot of people here seem pretty smart, so I'm wondering if anyone would have any insight or even sites that have insight. I'm not even sure how I'd plug this into Google.

edited 8th Dec '11 9:28:45 PM by Wackd

Write down everything that COULD be considered a story arc. Grade them based on the most objective thing you can think of. This won't provide quite enough information, so then get a panel of unbiased, uninformed subjects to read your notes and rank the story arcs on how story arc-y they are.