I analysed the number of viewers of all the completed seasons for the following tv shows: Fringe, Lost, Heroes, Gossip Girl, Vampire Diaries, True Blood, The Sopranos, How I met your Mother, Glee and Family Guy. The data was taken from the respective Wikipedia pages.
My aim was to find simple “rule-of-thumb” formulas to estimate key values from the number of premiere viewers and to see if there’s a pattern for the decline of a show. Below you can see the main results from the analysis.
Result 1: Finale vs. Premiere
The number of finale viewers is about 85 % the number of premiere viewers.
Result 2: Average vs. Premiere
The average number of viewers during a season is about 83 % the number of premiere viewers.
Result 3: Decline Pattern
The average number of viewers during a season is about 93 % the average number of viewers during the previous season.
This last result implies that the decline in popularity is exponential. If the average number of viewers for the first season is N(1), then the expected number of viewers for season n is: N(n) = N(1) * 0.93^(n-1). We can also express this using a table:
Average season two = 93 % of average season one
Average season three = 86 % of average season one
Average season four = 80 % of average season one
Average season five = 75 % of average season one
Average season six = 70 % of average season one
Of course, this is all just the sum of the behaviour of all the analyzed shows. Individual shows can behave very differently form that.