Yesterday's news about the death of Sherwood Schwartz got me thinking again about one of my favorite subjects, and an area where Schwartz excelled like few producers in the history of the medium:

Theme songs.

Simply put, no producer better understood the power of a catchy theme song than Schwartz. Whatever you may feel about the creative merits of "Gilligan's Island" and "The Brady Bunch (and I have too much childhood nostalgia for both to get especially judge-y), those shows will stick in the minds of everyone who ever watched them because of those explanatory theme songs, which Schwartz helped write. If anything, "Gilligan's Island" might not have even gotten on the air without that theme, as CBS executives worried that viewers wouldn't understand what this odd assortment of people were doing on an uncharted desert isle with not a single luxury. And there are arguably a bunch of high-concept '60s sitcoms and sentimental '70s family comedies that were otherwise about on par with the two Schwartz shows, but don't have the same enduring legacy because their themes weren't as catchy.

And that, in turn, led me to try my hand at a bit of advanced statistical analysis, and to create my own sabremetric-style acronym for this phenomenon.

Ladies and gentlemen, I give you TSORIS, or Theme Song Over Remainder In Show.

Without making it too complicated (I love Football Outsiders, but I'll be damned if I can grasp all the nuances of DVOA), with TSORIS I'm trying to calculate what percentage of a show's quality/legacy derives from the theme song versus all those other pesky elements like story, character, acting, catchphrases, etc. The catch, of course, is that everyone's TSORIS scores for shows will be different (this isn't like figuring out how efficiently Dirk Nowitzki gets his points), but then, my entire career is about subjective rather than objective judgments, so I can only get so close. Still, I thought it would be a good conversation-starter - and, if nothing else, an excuse for everybody to waste a lot of time watching YouTube clips.

Here's an assortment of theme songs from all over the TSORIS scale (and this is not a list of the best theme songs ever, to pre-empt all the "what, no love for...?" complaints):

"Gilligan's Island" - TSORIS: 81%
"The Brady Bunch" - TSORIS: 62%

Certain other aspects of "Gilligan" endure - the Ginger vs. Mary Ann debate, questions about why the Howells packed so much luggage for a three-hour tour, the show as metaphor for any other series that never does anything with a goal-oriented premise - but that song looms incredibly large in the show's legend. "Brady Bunch" has an even more memorable theme, but too many members of Generation X (and not just those of us who went into TV criticism) can describe too many storylines for the theme to get all the credit.

"The Rockford Files" - TSORIS: 44%

This is my absolute favorite theme song ever. (And the version embedded above is my favorite version of it, as I prefer this later, more guitar-driven mix to the one from the first season that pops up on all the theme song compilations.) And "The Rockford Files" itself is an all-time classic, arguably the best showcase (over "Maverick") for one of TV's greatest stars. (It's also the show where David Chase got his start, not that you see a ton of "Rockford" footprints on "The Sopranos.") There was a time in the '80s where it was, in fact, held up as TV's best drama ever (or, at least, I recall there was some kind of TV Guide cover story to that effect), though that says as much about the state of the TV drama then versus now as it does about the immense but formulaic charms of "Rockford." If I'd tried this concept 10-15 years ago, the show would likely have a lower TSORIS score, but it feels like we're so far removed from the glory days of Jim, Rocky and Angel that the theme takes on greater legacy importance than it once did.

"Hawaii Five-0" ('70s version) - TSORIS: 87%

I prefer the "Rockford" theme but won't object strenuously to anyone who wants to say this is the best theme ever. It's so cool, in fact, that it's hard to imagine CBS would have bothered to remake the show without it.

"Psych" - TSORIS: 97%

Your mileage will almost certainly vary for this one, as "Psych" has a lot of devoted fans. The shame of it is, I feel like I should be one of them, as so many aspects of the show - the cultural references, the sense of humor, and especially the fact that the theme (by The Friendly Indians, a band featuring "Psych" creator Steve Franks) is such an infectious piece of power-pop - feel like they were direct-marketed towards me. The problem is that I want to punch insufferable main character Shawn Spencer in the face whenever he's on screen and talking, and since that's pretty much the entire show, I can really only enjoy the theme (where you can see, but not hear, Shawn).

"Cheers" - TSORIS: 31%

Here's another classic (particularly the full version from above, as opposed to the truncated one that accompanies the syndicated repeats), and a perfect example of the philosophy that theme songs were there to make viewers happy they were about to spend 30-60 minutes with their favorite TV friends. ("Cheers" writer/blogger extraordinaire Ken Levine has the backstory on the theme, if you're curious.) But good as the song is, we're talking about one of the best sitcoms ever, and one where I think about so many other things - Norm's entrance lines, Sam and Diane arguing, Frasier losing his temper - before "Where Everybody Knows Your Name" comes to mind.

"Green Acres" - TSORIS: 42%

This is a score I imagine some people would assume to be higher, as "Green Acres" gets lumped in with CBS' other rural sitcoms of the mid-late '60s that featured earworm themes and mediocre comedy. But if you actually watched the surreal antics on and around Oliver and Lisa's farm - or if you know of the influence the show's style had down the road on the likes of "The Simpsons" and "NewsRadio" - you wouldn't give the song too much credit.

"Perfect Strangers" - TSORIS: 24%

The Miller-Boyett-produced comedies that proliferated across ABC in the mid-late '80s (see also "Full House," "Family Matters," "Step By Step," etc.) had a lot of common stylistic traits, but none more obvious than the uplifting theme songs that came with each and usually bore little resemblance to the show that followed. "Nothing's Gonna Stop Me Now" was the first of those songs, and probably the best, but "Perfect Strangers" as a whole is probably much better-remembered for Bronson Pinchot, the Dance of Joy and other things than for that tune. (Whereas "Step By Step" would have a TSORIS that might rival "Psych.")

"Mr. Sunshine" - TSORIS: 89%
"Lost" - TSORIS: 11%

With a few exceptions (like the aforementioned "Five-0" remake, and even it's significantly shorter than the '70s version), broadcast network shows have either done away with theme songs altogether or can only afford ultra-brief musical stings. (The 13-second "How I Met Your Mother" theme is almost shockingly long for today's environment.) The problem is that the commercial load for network series keeps increasing and increasing, and producers would understandably rather cut the opening title sequence rather than more story/jokes/etc. Still, some network shows turn the brevity to their advantage. "Lost"(*) used a brief, ominous musical sting by Michael Giacchino and his orchestra co-creator J.J. Abrams to set the tone for all the strangeness that followed, while "Mr. Sunshine" used five syllables - sung in a downbeat style belying the brief lyric - to establish the mindset of its misanthropic hero. The difference is that so much of the rest of "Lost" was memorable, whereas I imagine within 2 years all I will recall of "Mr. Sunshine" will be the theme - and that my mind will have convinced me the show was called "Mr. Sunshine Yay."

(*) I'm pretty sure, by the way, that the clip I chose is someone's recreation of the title sequence, as that seems to be all that exists on YouTube.

"How to Make It in America" - TSORIS: 93%

HBO's east coast answer to "Entourage" is amiable enough, but I honestly don't know if I would have watched past episode 2 or 3 were it not for the chance to hear Aloe Blacc's fantastic "I Need a Dollar" - and, for that matter, to see the great title sequence(**) that accompanies the song.

(**) Discussing title sequences as a whole - music and images - is a can of worms for another day. Though if anyone wants to come up with a good acronym/formula, I'm all ears.

So these are just a few examples of the theory in action. What are some of your favorite examples where the impact of the theme song was much greater than the rest of the show it accompanied? And, conversely, what are some of the best shows with the most forgettable theme songs?

Alan Sepinwall may be reached at sepinwall@hitfix.com