These are the questions I seek to answer:
"Are there more SF&F shows on now than in past years?"
"What is the longevity of a typical SF&F program?"
"What factors govern the amount and longevity of SF&F prime time programs?"
Methodology and Bias
I found that Wikipedia had a great collection of almanac articles that detailed the prime time lineup of every television network since 1946. I scoured the listings and attempted to catalogue every "North American prime time show whose premise was based on supernatural, fantasy, or science fiction elements." I endeavoured to have a consistent methodology that would mitigate sample bias.
As the programming trends in other countries and markets are quite different, and my focus was on North American television culture, most BBC and ITV shows were not on the list, unless I could find evidence of broad prime-time American syndication. Nor did I count Saturday morning kids shows and cartoons as they almost always contain fantasy elements and it would skew the data.
Also, there is more documentation available for more recent shows, so there is some accuracy biases between the years.
I logged the number of episodes produced, when known, rather than the number episodes aired. I did not include any "made for TV" movies or mini-series' as this was difficult to track consistently, and would bias the data to shorter runs.
I did not count shows that may have introduced a fantasy element late in its run, because that was not its primary premise, and again there would be a bias toward later shows that I have actually seen, and could identify this change. Though if it is documented that bulk of the episodes produced did have a sci-fi or fantasy element, despite some retooling, the show was added to the list.
Shows with a religious premise, involving Judeo–Christian elements such as angels and demons, may be included among the supernatural programs, if the cosmology presented was typically unique, and differed from established dogmas, which is most often the case.
Data and Results
I have identified 232 television shows that meet these conditions and criteria. Some minor trivia from my search: The first SF&F show was "Captain Video and His Video Rangers" from the Dumont Network in 1949. The oldest running SF&F program is Smallville, which started in 2001. The single series with the most episodes Bewitched with 254.
The raw data can be viewed on Google Docs, and I encourage any reviews, suggestion or further analysis of my data.
To answer my first question, I created the following graph showing the number of SF&S shows that debut in each television year, starting in September:
This graph shows a marked upward trend, indicating that, for the most part, more new SF&S shows debut every year. The 2007-2008 season brought 13 new shows, and 2008-2009 saw 14 new shows, the highest number of shows in my sample. But some recent years only posted a modest 3 or 4 new shows comparable to the volumes found in the late seventies or early nineties. A slight sinusoid can be seen with spikes at ten-year intervals, however more rigorous statistical calculations have not yet been done. But for there to be more new shows, it old shows must be cancelled.
The average longevity of these shows is estimated with arithmetic mean of 44.96, corresponding to an average of two, 22 episode seasons, which is a typical "full season". The median, or centre value is 22 episodes and the mode, is 13 episodes. Long running standouts such as Star Trek and Stargate, bring the average up, while the bulk of SF&F shows survive for only one season, as 14 is a typical "first order" of episodes before renewing for the rest of the season.
To see if SF&F shows typically get longer or shorter runs than police procedurals, westerns, medical dramas, or sit-coms, I would have to accumulate comprehensive data on those shows. However random sampling of non SF&F shows, which I had to take in order to determine their genre, indicates that most modern shows don't make it out of their first season alive. In the 70's and 80's, even if a show was tanking in the ratings, it would typically get all episodes aired, and then not renewed. In the last few years, the trend is to order fewer episodes up front, then pull shows after 3-5 episodes if ratings disappoint. Gone is the September season start, with mid-season replacements debuting throughout the year. In fact, a good portion of the shows announced for the 2009-2010 are already primed as mid-season replacements for shows that have yet to be cancelled.
I found some obvious-if-you-think-about-it trends regarding the kind of environment that creates more genre programming. For one, more broadcast channels are good for SF&F programming. When Fox started a national broadcasting schedule in 1987, there is a spike in the number of recorded programs, and the same can be seen when UPN and WB started in 1997. Likely more channels means more of every kind of programming, but importantly for this study, and fandom, SF&F was not overlooked by new general themed channels.
The history and trends in syndicated shows is not fully clear to me, but one can say that syndication is generally good for SF&F programming. Since syndication means that the initial financial burden is taken by a production company, the broadcaster can try out new shows with reduced risk. This leads a varied array of programming including, more often than not, SF&F.
Another big conclusion one can draw from this data is that Firefly, with only 14 episodes, is not an anomalously cancelled show, rather it has the longevity of a typical show in this data set. Its cancellation was not atypical of shows from that era, with none of the scripted shows debuting in that same year lasting until the current season.
If this survey suggests anything to those who love science fiction and fantasy programming on television, it is this: Treat every new episode of your beloved show as if it were the last, because history shows it may very well be. When your show ends, another one will come along soon.