A much more valuable tactic is to look at what various markets are accepting. For flash fiction, that's typically under 1,000 words (though for some, it extends to 1,200 or 1,500). For short stories, the sweet spot seems to be between 3,000 and 4,000 words with a hard cutoff in most markets at 6,000. Anything longer and you might as well push through into novella length.
Often I try to do it with a line from my WIP (kids Sci-Fi novel). And it’s a real challenge to squeeze in a snippet and make it fit. But plot does force one to consider the essentials of your snippet. Challenging but fun.
According to a rough analysis of HN comments, if readers relate to the first and second paragraph, they'll read it it through.
More seriously, this study is selecting on the dependent variable. No good.
john fox: concludes the article with a nice infographic that lays out the standard wordcounts from every
story size from "microfiction" to "Russian novel"; one of Munroe's stories is at the bottom end of the gap between "short story" and "novelette" with the rest well into "novelette" or "novella"
It doesn't help that the author uses lots of strong words and categorical statements.
As I recall it I read vol. 1 of Lord of the Rings in a single sitting
If you discover length clustering you may need to apply a separate classifier.