(FORTUNE Magazine) – If you didn't get out much in November, there's a very good reason: Every TV station in the country was conspiring to keep you in your Barcalounger. The networks put on their very best stuff (NBC gave us Daphne Zuniga as a CIA virologist! Fox gave us bears mauling children!), while local stations gave out thousand-dollar checks on the evening news.

The reason for this bounty is that November was a "sweeps month," one of the four months of the year when Nielsen Media Research supplements its weekly electronic monitoring of household television viewership with an intensive "diary method," which provides a demographic breakdown of viewership for advertisers. Since viewership drives ad dollars, every November, February, May, and July, stations pull out all the stops to glue as many eyeballs as possible to the set.

But despite the networks' unrelenting hype during sweeps month, the strange fact is that the networks don't benefit from them, at least not directly. The networks base their ad rates on the regular weekly data Nielsen produces year-round, so artificially inflating their ratings during sweeps doesn't have much impact on their year-round ad rates. For the networks, doing well in the sweeps isn't so much a matter of dollars as a matter of pride.

Smaller local stations, however, rely on sweeps for all their important ratings numbers. (Local affiliates in the larger markets, which make up some 60% of the country, do get some year-round research.) Local stations live and die by their ability to sell ad time during their local newscasts, especially their 11 o'clock evening news. The networks therefore put on their best stuff during sweeps in order to give smaller affiliates great lead-ins to their 11 o'clock newscasts. Since the sweeps months are so important for these local stations, it is hardly surprising that they tend to go a little gonzo to draw viewers to the set. While the tactic used to be simply to go for sensational angles during their evening newscast ("Local man marries dog! Film at 11!"), desperate affiliates have become even crasser: They now hold watch-and-win contests during sweeps months, whereby viewers are given lottery numbers and winners are announced during the evening news.

Now, there are plenty of flaws with the sweeps system, not the least of which is that the advertising community is not made up of fools. They know that the numbers they get during sweeps months have been artificially inflated, and take that into account when buying ad time on local stations. But the catch is, they don't know how much the numbers have been inflated--if they should deduct 20%, say, or 25% of the viewership on that night when channel eight's 11 o'clock news gave away $3,000 and ran its special report on baby snatching at the mall.

The networks, meanwhile, are sick of cramming all their good stuff into four months of the year, sending their best miniseries, movies, and Very Special Episodes into combat against other networks' best miniseries, movies, and Very Special Episodes. Viewers too, they say, are ill-served by the feast-or-famine menu of TV viewing that sweeps encourages--November gave us all-new episodes of every show; December, so far, has given us reruns and TV movies starring Henry Winkler and Antonio Sabato Jr.

But sweeps may be headed for the TV boneyard. Dave Poltrack, CBS's executive vice president for planning and research, is a prominent advocate of year-round nationwide monitoring of ratings. The issue, he says, is one of cost: Stations in smaller markets can't afford Nielsen's research year-round, which is why sweeps were created in the first place. Now, however, with sweeps becoming such a nuisance to all involved and the watch-and-win tactic rendering Nielsen's numbers ever more dubious, Poltrack believes he can muster enough support among the networks, ad agencies, and larger affiliates to pay for year-round research for the smaller affiliates, mainly by convincing them that everybody wins: "The networks and program makers get to maximize their product," he says. "And the agencies will have more meaningful numbers with which to make their buys." Poltrack hopes to have the beginnings of a plan drafted by January. If he succeeds, and ends sweeps as we know them, maybe--just maybe--Fox won't ever produce When Animals Attack! Part III. Dare to dream.

--Tim Carvell