What was going on when I was born?

Suburban Chinese restaurants have turned to New York City neighborhoods for the Chinese workers they cannot find in their own. Restaurant owners say they prefer Chinese workers, in part because they can more easily communicate with Chinese chefs and also because patrons expect to see Chinese waiters serving Chinese food. But they can't find such workers in the suburbs, they say, where many Chinese-American residents are doctors, lawyers or engineers. So every morning, hundreds of vans and station wagons from restaurants in northern New Jersey, southern Connecticut, Long Island and Westchester County pour into the city to pick up workers.

The Sports of The Times column yesterday incorrectly described a prize in the New York City Marathon. This is the first year that Mercedes- Benz cars will be awarded.

FOR a man who describes himself as ''less than a beginner in the playwriting business,'' Isaac Bashevis Singer figures that he hasn't done too badly. This weekend, for instance, he has two plays opening Off Broadway. ''A Play for the Devil,'' in Yiddish, will have its premiere tomorrow at the Folksbiene Theater. ''Shlemiel the First,'' which has been translated into English, opens Sunday night at the Jewish Repertory Theater. Mr. Singer, who received the 1978 Nobel Prize for Literature, sat in the American Restaurant, a cafe on the Upper West Side that he visits at least once, and sometimes twice, a day. It was 3 P.M. but the waiter put down a cup of split pea soup with croutons. ''Your favorite, Mr. Singer,'' he said. Mr. Singer spooned it slowly because he had already had lunch, ''a lttle something'' at home.

The Economy Nigeria cut the price of its major oil grade by $2 a barrel , to $28, becoming the first OPEC member to break the official price structure set 18 months ago. Earlier in the week, Britain and Norway cut their oil prices. Reaction in foreign-exchange, stock and credit markets was swift, with traders believing that a general oil price break is inevitable. (Page A1.) Personal income rose 0.9 percent in September and consumer spending climbed 1.4 percent. The spending increase followed two flat months and was the biggest since last April. (D14.)

Friday POLITICAL SKITS ON 42D ST. A political cabaret put together and acted by alumni and friends of John Houseman's Acting Company, including Christopher Durang, Marian Seldes, Margot Harley and Mark O'Donnell, opens tonight at 11 in the Studio Theater at Playwrights Horizons, 416 West 42d Street. It is called ''Issue? I Don't Even Know You!,'' and among the skits is one on charisma - a politician switches topics as meters hooked to some of his listeners indicate they're getting bored. The cabaret's participants are volunteering their services for the production, which will benefit the Women's Campaign Fund, a bipartisan organization that supports women in the early stages of their political careers. Fridays and Saturdays at 11 P.M., Sundays at 7, Mondays at 8 until Election Day. Tickets: $10. Reservations: 279-4200. Information: 564-3510. ASIAN JAZZ FESTIVAL

President Reagan ordered two investigations today into whether the Central Intelligence Agency acted improperly in preparing a manual for Nicaraguan rebels that includes advice on kidnapping and killing public officials. One investigation is to be by the C.I.A.'s Inspector General and the other by the agency's oversight board. Larry Speakes, the White House spokesman, said in a statement, ''This Administration has not advocated or condoned political assassination nor any other attacks on civilians, nor will we.'' He added that the investigations ''will determine whether there were violations of law or policy and whether there were any managerial deficiencies.''

New York City's Department of Investigation released a 1983 report yesterday that criticized Benjamin Ward, now the Police Commissioner but then the city's Correction Commissioner, for using his office for ''late night and weekend meetings with a female guest.'' Mr. Ward yesterday acknowledged the accuracy of the report, which also criticized him for using city employees to help him make repairs on his private boat. The report also said the Commissioner had stored the boat, which Mr. Ward said he purchased for $400, in a city-owned garage on Rikers Island. Mr. Ward said he agreed with the report, which said he had exercised poor judgment. ''He concluded that I exercised poor judgment,'' Mr. Ward said of Patrick W. McGinley, the Investigation Commissioner. ''Quite frankly, I agree with him.''

Salvadoran Army units today opened the first major offensive against leftist guerrilla forces since rebel and Government officials met three days ago to discuss ways of ending the war here. The offensive ended a period of relative calm in the country as Government and guerrilla forces appeared to be considering the results of the talks in the northern Salvadoran town of La Palma, the first such meeting between Government and rebel officials. ''The war goes on,'' said Lieut. Col. Domingo Monterrosa, army commander of the eastern third of the country, as his troops moved into rebel-held northern Morazan Province here today. ''There are times when you have to make war to gain peace.''

A six- month, $426 million increase in the rates local telephone companies can charge long-distance companies for services was proposed yesterday to the Federal Communications Commission. If approved, the increase would take effect Dec. 1. A portion of the increase proposed for the American Telephone and Telegraph Company would be reduced next summer in conjunction with the F.C.C.'s expected imposition of a fixed monthly charge to local residential customers for access to their local phone company's equipment, the rate proposal said.

''This Administration has not advocated or condoned political assassination nor any other attacks on civilians, nor will we.'' - Larry Speakes, the White House spokesman. (A1:4.)

Sir Richard Stone, a retired 71-year-old Cambridge University professor, today won the Nobel Memorial Prize in Economic Science for his work to develop the systems widely used to measure the performance of national economies. The five-man Nobel selection committee described Sir Richard as the person mainly responsible for creating an accounting system for nations that has been indispensable in monitoring their financial position, in tracking trends in national development, and in comparing one nation's economic workings with another's. The systems of national accounts - known to most economists as S.N.A.'s - have been pivotal in the work of such international organizations as the United Nations, the International Monetary Fund, the World Bank and the Organization for Economic Cooperation and Development. The essence of Sir Richard's system was to develop double-entry bookkeeping on a grand scale: statistics were to be gathered and processed so that what one sector of the economy spent would show up as income somewhere else, and so that savings could be related to investment. Households, businesses and government were all to be included so that the distribution of spending and income among them would be clear, as well as the nation's balance of payments with other nations.

-1926) is an extraordinary saga. Not only did she manage to surmount the handicaps posed in America by her gender and gentle breeding to make a full-time profession of art; she also became the only American to play an active role in the French Impressionist movement (and, by advising prominent friends on their collections, she helped bring it to this country). There has not been a Cassatt show in the neighborhood since 1973, when the Metropolitan Museum of Art set out the works in its collection, after the big Cassatt retrospective at the National Gallery in 1970. Now, a chance for a fresh look at this indomitable talent is provided by ''Mary Cassatt: An American Observer,'' at the Coe Kerr Gallery, 49 East 82d Street (through Oct. 27). Comprising some 30 oils, pastels and watercolors, the show in cludes such well-known canvases as ''At the Opera'' (1879), a dashing close-up of a woman in an opera box, acquired by the Museum of Fine Arts in Boston as early as 1910. But alas, it leaves out, except for one example, the etchings and color prints inspired by Japanese masters that were her most original contribution.