Ever wonder what anime get sequels and what don’t? The simple answer to this fairly simple question is “sales, plus a few mitigating lesser factors”. We know this, beyond the obvious intuition, because over the years, we see those with robust sales totals get continued much more often than those with lackluster ones:
A more interesting question is perhaps this; which anime this year have the best chances of getting continued? After some delving into the subject, I can finally answer this question to a respectable degree of confidence. Based on data from 615 shows airing from from 2005-2012, the first season of an anime which sells x units per volume has P odds of getting a sequel, meaning either a second season or a movie.
P(x, t, L)=.01+θ(x-2250)*(.7-1650/(x+L*750))*e^(-((t-1)*θ(t-1))/.7)
Where t is the time in years passed since the first season aired, and L=1 corresponds to the series having been licensed. θ is the step function, 0 when the number inside the brackets is less than 0, and 1 when the number inside is greater than 0.