What was going on when I was born?

America's economy has developed a split personality - languid in manufacturing but dynamic in the services sector - that complicates efforts to stimulate production, economists say. ''The two-tier economy is very clear-cut,'' said Walter K. Joelson, chief economist of the General Electric Company. ''We're in recovery, yet industrial production is as flat as an ironing board. So you have to ask yourself what the dickens is going on. If industrial production is not expanding in a recovery, it sure isn't going to expand in a recession.''

Because of an editing error, an article on Saturday about arguments over control of United Press International left unclear the affiliation of an executive who said Reuters had expressed interest in acquiring only the photo and radio news networks of U.P.I. The executive was at U.P.I.

''The operation is over and was successful. We don't like trading lives like this, but at least 1,153 people who were prisoners yesterday are free today.''

Seven people, including a 4-year-old boy and four teen-agers, were wounded in bursts of gunfire on a busy Chinatown street last night, and the police later said the shootings were an apparent outbreak of gang warfare. Five of the victims - the child, who was shot in the head; three of the teen-agers, and a 37-year-old man who was shot in the chest as he dined in a restaurant - were listed in critical condition last night. In Chinatown, where youth gangs have been responsible for extortion, murders, kidnappings and other crimes, the shootings were the worst outbreak of violence in more than two years, according to law-enforcement authorities. The number of gunmen was not immediately known, but witnesses told the police they saw at least one assailant running from the shootings, which erupted shortly after 6 P.M. on East Broadway between Catherine and Market Streets, just south of the Manhattan Bridge on Chinatown's southeastern edge.

The Supreme Court ruled today that The Nation magazine infringed the copyright on the memoirs of former President Gerald R. Ford by printing unauthorized quotations from the book several weeks before the 1979 publication date. The 6-to-3 decision overturned a ruling in the magazine's favor by the Federal appeals court in New York. That court, the United States Court of Appeals for the Second Circuit, ruled in 1983 that The Nation's verbatim use of 300 words from the memoirs, within an article of 2,250 words, was acceptable under Federal copyright law as news reporting on a subject of public interest. Writing for the Supreme Court today, Associate Justice Sandra Day O'Connor said that ''no author may copyright facts or ideas.'' The Nation had ''every right to seek to be the first to publish information,'' she said.

The stock market surged yesterday in an enthusiastic response to lower interest rates, propelling the Dow Jones industrial average to its first close above the 1,300 level. The Dow average of 30 industrial stocks, the most widely followed market indicator, rose 19.54 points, to 1,304.88, surpassing the previous record of 1,299.36, set on March 1. Market analysts said the rally reflected the encouragement that investors drew from the Federal Reserve Board's announcement late Friday that it was reducing its principal lending rate -the rate it charges financial institutions to borrow money - to help rekindle a sputtering economy. Earlier Than Predicted The half-point cut in the discount rate, to 7 1/2 percent, had come earlier than most analysts had predicted. Banks across the country quickly responded by cutting their prime lending rates - the benchmark for many consumer and commercial loans - to 10 percent from 10 1/2 percent.

Palestinians and Shiite Moslem militiamen fought fierce battles here today, and the Lebanese police said about 60 people were killed and 270 wounded. If the Palestinians are defeated in the fighting between the two Moslem groups - most of the Palestinians are Sunnis - the last force challenging Shiite authority in West Beirut will be eliminated. The clashes, fought with rocket-propelled grenades, mortars and anti-aircraft guns, took place around two Palestinian refugee camps in West Beirut, Sabra and Shatila, and Burj al Brajneh, just south of the city. Sabra and Shatila are where hundreds of civilians were massacred by Israeli-backed Christian Phalangist militiamen in September 1982.

An article in Metropolitan Report on Friday about plans for a new experimental high school program in East Harlem misidentified the position now held by the program's new director and misstated the site. The director, Deborah Meier, is now director of an alternative school at P.S. 171, not principal there. The experimental program is to be offered at the newly designated Jackie Robinson Educational Complex, a former junior high school at 106th Street and Madison Avenue.

A picture on Saturday with an article about military spending was published erroneously. It showed Dr. Stanley I. Weiss, a former official of the National Aeronautics and Space Administration, not Stanley A. Weiss, chairman of American Minerals Inc. and president of Business Executives for National Security.

PETER, in his late 30's, is a smooth talker who seduces women for their money; his motto is ''Pleasure is where it's at.'' Paul, his twin, is kind and decent, and prides himself on caring for people in need. David, in his early 20's, is a highly talented sculptor. Tom, a teen-ager, is so mechanically adept that he can pick a five-tumbler lock with a paper clip. Dorothy, a frightened 10-year-old girl, is prone to run away from home.

The Senate tonight responded to mounting criticism of military spending practices by approving without dissent an amendment to make significant changes in the way the Pentagon does business. One important provision of the wide-ranging amendment would bar Government employees from dealing with contractors who approach them about jobs. Another change would require the military to use competitive bidding on more contracts. The proposals were adopted by a vote of 89 to 0 as an amendment to a bill that would authorize $232 billion in military programs.

AT a time when many people have been sending their children to school at an earlier age, a growing number of parents are deciding to have their children start school a year later. They have been following the advice of a group of educators who say that many children who have academic problems in later years could have avoided them if they had simply started kindergarten at, say, the age of 6 rather than 5. Led by Louise Bates Ames, associate director of the Gesell Institute of Human Development, a private research center in New Haven, those educators say that children should be placed in school based on what Dr. Ames calls their behavioral rather than chronological age. Dr. Ames, a child psychologist, and other proponents of the idea say that because children mature at different rates, how old they act should be more important than how old they are. ''Little bodies are not geared for academic tasks,'' which, more and more, are required in kindergarten, said Marie Williams, a psychologist with the school system of Fairfax County, Va. No matter how bright, she said, some 4- and 5-year-olds may not be socially ready for school, physically coordinated enough to handle the paper work or patient enough to sit still at their desks.