• by Joe Mandese  @mp_joemandese, November 13, 2012

While a small matter compared with the loss of life, homes and other property caused by “superstorm” Sandy, two weeks after the nation’s largest media markets were essentially knocked off the grid, Nielsen has finally begun disclosing some of the impact it has had on the national and local TV marketplaces. While Nielsen executives say they are still assessing the full impact, they began notifying some customers late last week that among other things, Nielsen would not “release November 2012 survey data for the New York DMA,” the nation’s largest media market, accounting for nearly 6.5% of the U.S. population.

A Nielsen spokesperson said some customers would still have access to some of the data for specific days in November that pass Nielsen’s statistical guidelines for reporting, but could not confirm exactly which or how many days would be involved, or what the impact of those statistics would be.

Nielsen also informed clients that it is still evaluating which days will be excluded from the “survey data” it reports for at least four other major markets -- Philadelphia (ranked No. 4), Boston (No. 7) Cleveland-Akron (No. 18) and Baltimore (No. 27) -- which, like New York, are part of Nielsen’s so-called “local people meter” samples. Those local people meter panels are also part of Nielsen’s 20,000 national people meter sample, and add up to more than 13% of Nielsen’s total national sample, which is the basis for billions of dollars worth of broadcast and cable TV advertising deals.

It is not clear how the storm, as well as a subsequent Northeaster that also knocked power out in the region, may have affected other households along the Eastern Seaboard outside of those five LPM markets, or how other meter/diary and diary-only ratings markets would ultimately be impacted by the effects of the storm -- but to strike a metaphor, Sandy is clearly proving to be the storm of Nielsen’s Century.

The effects -- pulling an entire month of survey data for the nation’s largest market, removing some from others, and potentially needing to revise national TV ratings and universe estimates -- are without precedent, especially since this comes during one of the most valuable advertising periods of the television calendar year, the start of a new season, as well as the November sweeps, when ratings for many smaller TV markets are set for an entire quarter.

The loss of Nielsen households happened two ways. One was when Nielsen homes in metered markets lost power and the batteries on their electronic meters drained, or when homes in the sample were literally destroyed or the families living there were relocated.

Nielsen has experienced the devastation of storms on its sample before. Last year, it had to pull significant amounts of data in markets affected by Hurricane Irene, and the impact of Hurricane Katrina was so severe that when a significant percentage of its population was permanently relocated, New Orleans actually dropped from the 43^rd largest media market in the U.S. to 52^nd. It has subsequently moved up to 51^st following some population gains.

A Nielsen spokesperson said it was too early to assess the ultimate impact of Sandy on either local markets or the national ratings, and conceded that “we need to have better answers.”

Asked why it is taking more than two weeks to get those answers, when Nielsen claims that it has systems sophisticated enough to know what its daily “in-tab” -- or the percentage of households that are actually reporting data in its tabulations -- are, the spokesperson did not comment.

But the implications are clear that Sandy has severely impacted both the nation’s largest TV market, as well as the national TV advertising marketplace by some level of magnitude that was serious enough for Nielsen to pull the entire survey period from its November books.

One Nielsen client said those moves raise questions about how Nielsen has been estimating and reporting ratings since the storm, including some especially high-profile events of “national interest” like the TV industry’s presidential election night coverage.

“The presidential election of 2012 has been decided without a recount,” he said, adding: “Nielsen will not be so lucky.”