Only 6 Plots?

A recent article cites the results of exhaustive study of popular literature and concludes there are only 6 basic plots. Based on their methodology, that's what they had to conclude, I believe.

http://www.dailymail.co.uk/sciencetech/article-3679510/There-just-SIX-plots-film-book-TV-

They followed the trends of the story lines in terms of rising (R) or falling (F). To capture an arc, rather than just a continuous trend, they used up to a three-part pattern, for example, FRF would be falling, rising, falling again. RF would be rising but then falling.

Let's enumerate the three-phase possibilities and then give their triple-, double- or single-phase equivalents:

FFF = F
FFR = FR
FRF = FRF
RFF = RF
FRR = FR*
RFR - RFR
RRF = RF*
RRR = R

So, out of 8 possibilities, only 6 are unique, with 2 that are duplications.

So, of course they found only 6 plots.

If they allowed 4-phase options, like RFRF, they would have found 16 possibilities, but some of them would have effectively been duplicates, such as RRRF and RRFF, which boil down to RF, etc.

Sometimes the analysis dictates the results. If we specified the plots as being either where the outcomes are happy or unhappy, we'd have only two. If we allowed "equivalent," we'd have three. If we said the protagonist started happy or unhappy and then got happier or unhappier or remained the same, we'd have six. You get the point.