It seems hard to believe, but People magazine is five years old this week.

The debut issue went on sale Feb. 25, 1974, with an initial circulation of one million -- the biggest kickoff figure in magazine history. The slick, zippy, picture-heavy weekly now sells 2.3 million copies every seven days with a passalong readership of 18.3 million. It's the 20th best-selling magazine in the country, the third biggest profit maker for newsdealers, and last year surpassed sister publication Time in advertising.

People's celebrity-conscious covers tend to be good barometers of public interest. Its five best sellers have been Cher, Gregg & Baby (9/27/76); Tony Orlando (10/3/77); Star Wars (7/18/77); Priscilla Presley (12/4/78) and a tie for fifth between Kris Kristofferson & Barbra Streisand (1/10/77) and Liz Taylor & John Warner (2/1477).

Although the magazine won't discuss worst sellers, sources at People say a Howard Cosell cover was probably the biggest clinker.

To celebrate its anniversay, the magazine commissioned an independent -- and fascinating -- poll of its readers' preferences and prejudices. Some of the findings:

Best lookers: Robert Redford and Jaclyn Smith.

Most boring people on TV: Howard Cosell, with Johnny Carson a virtual tie, and Farrah Fawcett-Majors.

What fashion fads drive you up against the wall: heavy makeup and purses for men.

Who would you like to see as president: Ted Kennedy, with Gerald Ford second, and Ronald Reagan and Jerry Brown tie for third.

Favorite singers: Billy Joel and Linda Ronstadt.

Would you want to be or want to marry Jackie Onassis: Women, 88 percent no; men, 78 percent no.

Ms. Onassis

Moving right along, Ms. this month offers "the first authorized cover story on Jacqueline Kennedy Onassis since she left the White House" and quickly makes it clear why this woman hasn't been on more authorized covers.

First, we have Ms. editor Gloria Steinem marveling over Onassis' penchant for getting her own coffee and doing her own Xeroxing at the office -- not to mention "crawling around the floor, arranging picture layouts." Then we have Ms. Onassis' own reflections on "why women work," a brief piece that manages to plug seven of her publisher's books in an essay of less than 900 words.

What magazine needs to hand out free ads like that?

Book bombs

On the literary scene, the annual survey of Christmas returns in the. Feb. 19 Publishers Weekly documents which books were real stinkers in 1978.

The hands-down loser was Mario Puzo's "Fools Die," a big tals of the rise to fame and fall of a writer with a heavy gambling habit. Before publication, the novel set a record with a paperback sale of well over $2 million.

In non-fiction, "The Muppet Book" was a big stiff, along with Betty Ford's "My Story" and a $50 book of Avedon fashion photographs.

Retailers also got stuck with crates of "Star Wars," "Close Encounters" and Tolkien calendars.

Statistical Sense

Two new publications:

American Demographics, in a neat, orderly way, attempts to make some sense out of the zillions of statistics available from government and private agencies. In its first two issues it has pointed out mathematical problems with government estimates on minority populations, relates population to the gross national product, discusses difficulties with birth-rate trends, and comments on the population of China and the attendance statistics on the traveling Tut exhibit. $30 annually from Box 68, Ithaca, N.y/. 14850.

The TAB (for "adult business") Report is a monthly compilation from the Washington publisher of "Federal Contracts Opportunities Reports," aimed primarily at entrepreneurs who are involved in the adult-oriented world of porno shops, film theaters, massage parlors and the like. The report summarizes court actions ("Seizure of Projectors Ruled Illegal," "Customer of Prostitute Arrested after Going to Police"), provides financial tips (are dance hall girls subject to withholding tax or independent contractors); displays new products and services ("Indiscreet Undergarments -- Underwear That's Funtowear...") and includes a classified section "Escort Service in New York expanding to other cities..."). $48 annually from 1228 Half Street SW, Washington, D.C., 20024.

Sox-Struck

The agony of the Yankee-Red Sox pennant race is mesmerizingly conjured up by disc jockey Jonathan Schwartz in the Feb. 26 Sports Illustrated. An insatiable Sox fan, Schwartz calculates that he has spent nearly $15,000 on long distance calls to listen in to radio broadcasts of the action. "In a hotel in Paris I heard George Scott strike out in Seattle," he writes, as a prelude to a richly detailed account of the season's final playoff game. The ticket alone cost Schwartz $150 and a copy of Frank Sinatra's rare "Close to You" album.

Reflecting on the season, Schwartz recalls:

"I had wept and raged. I had participated in two fist fights, had terminated a close friendship and had gone out in search of a neighborhood 15-year-old who had written RED SOX STINK in orange crayon on the back window of my car. I had set out after him with vicious intent, only to return home in a minute or so, mortified. The psychiatrist, whom I immediately sought out, said to me, "This is not what a 40-year-old should be doing with his time. Comprenez-vous ?'"

Omniscience

We're in for a female president in 1992, a man landing on Mars in the same year, and $1-a-gallon gas by 1982, if the readers of future-oriented Omni are on target.

The opinions of a startling 20,000 readers, who responded to a question-naire, are summarized in the magazine's March issue Ninety percent foresee ESP as fact rather than fiction, think life expectancy will reach 100 by the year 1998 and predict that a computer will win the world chess championship in 1985.Commercial flights on orbiting spacecraft are expected in the 1990s, a decade after the readers see cloned human beings becoming a reality.

Tillers and Snakes

With the gardening season rapidly approaching, we're willing to recommend one publication that's free for the asking: The Troy-Bilt Owner News, an incredibly unorthodox tabloid from a company that manufactures a rear-tined tiller.

What must be accepted as prolegomenon is that several of the articles in each issue detail ways to use the company's own products (which this gardener is perfectly willing to endorse). Beyond that there are scores of letters filled with practical suggestions (keep rabbits out of your garden with rubber snakes), articles on fertilizing routines and wide-row planting and, in the February issue, an exhaustive, annotated list of American seed companies and excerpts from a book on solar greenhouses.Free from Garden Way, Inc., Troy, N.Y. 12180.

Laughs and Linage

The American Spectator offers an hilarious spoof of Esquire's Irving Kristol profile in its March issue... Meanwhile, editor Byron Dobelle has returned to Esquire from Life magazine... Convenience stores like 7-Eleven sell more magazines than any other type of outlet... Playboy has accquired the half-million circulation Games magazine... High Times, the drug-oriented magazine, has formed a search committee to find a new publisher, a post vacant since founder Tom Forcade committed suicide Nov. 17... Magazine advertising revenue for 1978 increased 20 percent over the previous year, up to $2.374 billion.