A Brief History of Sweeps Week

A Brief History of Sweeps Week

Ah, sweeps week — that time of year where plot lines get thrown out the window as network executives feverishly pray that ratings will follow them through the roof. Four weeks a year, networks inundate the TV-viewing public with a veritable flood of plot-twisting, cringe-inducing, shark-jumping moments in the hopes they’ll tune in — please, just tune in — in order to give the networks a vital boost during the critical periods when Nielsen Media Research takes its regular survey of TV viewing habits.

This year, sweeps week itself is a twist. Because of concerns over the planned transition to digital TV signals , Nielsen has moved the start of sweeps to March 5, several weeks later than usual. The signal transition ended up being delayed until June, but Nielsen opted not to change the schedule again.

Calling it sweeps week is a bit of a misnomer; it’s actually nearly a month. The current period won’t end until April 1. It’s the result of an anachronism: Nielsen developed the concept of sweeps week in 1954, when they mailed small TV ratings booklets to households across the country and asked them to record everything they watched for a week. To keep the task of receiving and recording thousands of diaries from the sample households, they started a “sweep,” starting on the East Coast and moving across the country over the course of four weeks. Now computers make the data gathering and recording a cinch, so Nielsen surveys each market continuously for the entire four weeks.

Networks use the data Nielsen gathers during each period to set local advertising rates; national rates, which comprise the bulk of TV ad revenue, are set separately and based on year-round data from select families. Still, local ads are a big chunk of a TV network’s revenue, so when sweeps week — er, weeks — roll around, they try and game the system by doing just about anything to make sure you tune in.

Some examples E.R. performed an entire episode live in 1997; the camera crew caught in the background was explained away as a PBS documentary crew filming in the hospital. The same year, Ellen DeGeneres came out as a lesbian on her sitcom Ellen, and networks even distributed special glasses around the country and showed some episodes in 3D, an experiment that largely fizzled.

Sweeps even has its own terminology: “stunt casting”, which pulls a high-profile star in for a short cameo or story arc. In 2003, former Superman Christopher Reeve briefly appeared on Smallville in 2003, playing a scientist examining the young Clark Kent. A show “jumps the shark” when its ratings stunts smack of desperation. The phrase was inspired by a a three-part Happy Days special in 1977 in which Fonzie jumped over a shark pen on water skis. and which fans point to as the specific moment the show started its decline.

Advertisers sometimes complain that all the stunts create skewed ratings and more expensive advertising costs. Technology certainly exists to record ratings year round, and it may only be a matter of time until Nielsen is pressured into switching their model. But for this particular sweeps period, there are few concerns — it promises to be one of the least eventful sweeps ever. Because of the rescheduling — most winter sweeps periods occur in February — there’s no data set to directly compare this year’s ratings against, making these particular measurements less important in setting advertising prices. So expect fewer spectacles and gimmicks from the networks: Pam won’t be marrying Jim, Jack Bauer won’t die and the castaways on Lost won’t do something inexplicable and improbable. Expect the uneventfulness to continue until April 23, when the spring sweeps period begins.

See TIME’s pictures of the week.