Mark J Penn is the polling analyst famous for helping Bill Clinton to re-election in 1996 by identifying 'soccer moms' - busy, smart suburban women - as a crucial, overlooked sector of the electorate.
Dubbed 'the guru of small things' by The New York Times, Penn has built a career on his ability to spot the social ripples far out at sea that might one day become big waves. In his latest book, Microtrends, he contends that 'by the time a trend hits 1%, it's ready to spark a hit movie, bestselling book or new political movement'.
The 75 small but influential trends examined in Penn's book include some fascinatingly counter-intuitive examples.
Few people would guess Mexico sends the largest number of Protestant immigrants to the US, or that more adult women play computer games than boys aged 17 or under, or that the average Palestinian suicide bomber is better educated and better off than the average Palestinian, or that the best-represented income group among tattooed Americans is people making $75,000 or more.
Most bookshops file Microtrends with the inspirational business titles, and there is plenty of data here for marketing execs and ad men to chew on. But I found myself running with Penn's hit-movie hint, and mining his examples for their plot potential.
Take his chapter about pro-Semites: in a 2006 Gallup poll, US approval ratings for Jews were higher than for any other religious group; more interestingly for blocked rom-com scriptwriters, 11% of members of online Jewish dating service J-Date are non-Jews - many of them, it appears, Catholic men. Something that might once have made for a hilarious scene in an early Woody Allen film is suddenly a statistic.
Or what about late-breaking gays' We're used to hearing about the trauma of coming out to one's parents, but according to Penn, the opposite scenario is almost as common: 3.5 million US kids have had to come to terms with mum or dad being gay. The TV movie Jack (2004) dealt with the issue head-on and a handful of other films have used it as a plot twist, but it is definitely an underused dramatic premise.
Not all microtrends pass under the script radar. Some become fashionable - like the fad for male nannies in TV shows (Friends, Ally McBeal) despite the fact that, for Penn, this is more of a nanotrend: it's actually surprising how few male nannies there are in our egalitarian times.
The US boom in teenage knitting and crocheting, on the other hand, has had oddly little coverage from teen-friendly directors such as Gregg Araki or Catherine Hardwicke.
Maybe this is because knitting is less filmic than skateboarding, but I suspect it also has to do with a tendency, even among the least mainstream writers and directors, to take stereotypes for facts.
Here's another example: plenty of admirable US indie films - Half Nelson and the recent Ballast spring to mind - touch on the problems faced by young blacks growing up in depressed communities where drug dealing is the only flourishing economic activity, but very few illustrate another of Penn's microtrends - the fact 'young blacks are doing better than ever in America'.
One might argue that, at least in the US, television is now the place where the nation deals with the sort of emerging social trends that once generated films like Guess Who's Coming To Dinner.
We're more likely to see a prosperous, middle-class black family on Desperate Housewives than on our cinema screens (okay, the African American family in Desperate Housewives keep a son locked up in the cellar, but the white residents of Wisteria Lane aren't exactly saints either).
But the pendulum could swing back. Here's a microtrend prediction of my own: the time may be ripe for the return of small, intense, 1950s-style social-issue films like 12 Angry Men or Bigger Than Life.
But producers and distributors shouldn't assume they will only play well with the affluent urban liberals. As another of Penn's counter-intuitive pollster factoids reveals, it's the working classes who pay most attention to the issues, rather than the personalities, in US political campaigns.