This article was updated at 7:09 p.m.
NEW YORK — Pay TV’s had a dirty little secret, but Nielsen will put an end to it in January.
That secret: Every time the press reported the rating of a show on HBO, Showtime, Cinemax or TMC, the number included viewing on the multiplex channels of the four pay networks in that specific time period.
The networks were not engaging in deliberate deception; Nielsen Media Research just didn’t have the technology to break out the main premium network from the array of additional plexed feeds. HBO’s digital subscribers, for example, typically get at least six other plexes for their monthly fee: HBO 2, HBO Signature, HBO Comedy, HBO Family, HBO Zone and HBO Latino.
The networks argue that multiplex viewing was not a big problem because the media were interested mainly in the high-profile pay TV shows that most subscribers homed in on, like an original episode of “Sopranos” on HBO, the premiere of “The Reagans” miniseries on Showtime or the first showing of Steven Spielberg’s “Catch Me if You Can” on Cinemax.
According to this argument, the safe assumption is that 90% or more of the network’s viewers are tuning in to these appointment programs and ignoring whatever movies or TV shows are turning up on the plexes at the same time.
But as of next month, the published Nielsen ratings will provide an accurate picture of the audience pulled in by, for example, the final eight episodes of HBO’s “Sex and the City” on Sunday nights.
Then, an annoying new problem will surface: Comparisons between the 2004 “Sex and the City” rating and its 2003 equivalent will be impossible, as last year’s figure was inflated — however slightly — by the multiplex add-ons.
Since the pay TV networks don’t accept advertising, they employ ratings data differently from ad-supported networks. HBO’s and Showtime’s concern is in satisfying subscribers and keeping them from canceling when they get their cable bills each month.
HBO kept renewing the low-rated “The Larry Sanders Show” for a number of years because it grabbed an upscale, educated audience; got mostly rave reviews; and picked up a fair share of Emmy nominations.
And Showtime kept “Resurrection Blvd.” on the air longer than its relatively small ratings would justify because a disproportionate number of Hispanic viewers were subscribers to the network.