What was going on when I was born?

In an effort to improve Nicaragua's business image, Joaquin Cuadra, Nicaragua's Minister of Finance, outlined new foreign investment rules yesterday. He described them as more favorable to foreign companies than the investment policies of the regime of Gen. Anastasio Somoza Debayle. The new rules, which Mr. Cuadra discussed in an interview in New York, are the first formal set of guidelines from the Sandinist Government for new foreign investment since the Sandinists seized power in 1979 with the ouster of the Somoza family. Mr. Cuadra said that foreign investors would be allowed to own 100 percent of any operations they established in the country - in contrast to Mr. Somoza's policy of taking a 50 percent share - and would be permitted to repatriate profits.

An article Saturday on the Reagan Administration's cancer policy incorrectly identified Frederica P. Perera. She is a senior staff scientist for the Natural Resources Defense Council.

The elimination within the next month of ceilings on the amount of interest banks may pay on certain consumer checking and savings accounts is expected to have profound effects on the economy. While many consumers will benefit from higher returns on their federally insured accounts, many also might have to pay more for their credit as a result of the pending changes. ''It's going to be a mixed blessing for the consumer,'' said Irwin L. Kellner, senior vice president and chief economist for the Manufacturers Hanover Trust Company. ''For savers, it will offer an opportunity to obtain higher rates than before, but it will result in higher rates for borrowers because, obviously, it means banks' cost of money will be higher than it otherwise would be.'' The nation's financial structure, itself, could also be significantly changed as a result of the decision by Federal regulators on Monday to authorize an account that has no interest rate ceiling. Except for requiring a $2,500 minimum balance, the account, which will be offered beginning Jan. 5, will be indistinguishable from ordinary checking accounts.

A new dispute over the Lincoln West housing project - involving the developer's promise to pay for remodeling the cramped IRT subway station at 72d Street and Broadway - has arisen between City Council President Carol Bellamy and the Koch administration. Miss Bellamy charged that the developer of the $1 billion housing complex along the Hudson in Manhattan had been granted a possible delay in putting up $29.5 million for the station work because of ''unilateral action by a deputy mayor.'' She referred to Deputy Mayor Robert F. Wagner Jr., who said yesterday that the builders had already put up $2 million for a study of the remodeling, then had asked that the rest come due either when they got their first building permit or when the Metropolitan Transportation Authority was ready to spend the money, whichever came first.

Americans reduced their outstanding consumer debt in October for the first time in 10 months, lowering the total debt by $324 million, the Federal Reserve reported. It cited a $350 million drop in cash loans outstanding from banks and certain finance companies. Credit for auto loans also declined. The figures were seen as evidence of continuing consumer caution. (Page D1.) Senate Democrats proposed a public works job program as a substitute for the House-passed highway improvement plan, which is supported by the Reagan Administration. The three-year, $17.9 billion Senate measure would be more expensive and more wide-ranging than the House measure, which would be financed in part by a 5-cent rise in the Federal gasoline tax. (A1.)

Alcoholism-rehabilitation centers across the nation are adopting a new style of therapy - treatment of the family as a whole. Its practitioners believe such treatment raises the long-term recovery rates of alcoholics and helps their family members as well. The increasing emphasis on the involvement of families in a variety of ways during the recovery process, according to some alcoholism experts, is transforming the nature of treatment in America. Some researchers believe First of two articles on a widening form of alcoholism treatment. that the use of family therapy is helping to heal the historic rift between mental-health professionals and alcohol-rehabilitation counselors, many of whom have been traditionally skeptical of recovery strategies not based on the precepts of Alcoholics Anonymous. Family therapy isn't a ''magic bullet'' or miraculous cure for alcoholism, said Dr. Peter Steinglass, professor of psychiatry and director of family-therapy training at George Washington University School of Medicine. ''It's important to establish a cautionary tone,'' he said, ''though my own feeling about the use of family therapy is that it's definitely the wave of the future. All the studies thus far have displayed great enthusiasm for the continued use of family therapy.''

A police case involving a North Korean diplomat who has been secluded in his country's mission in Manhattan for almost three months rather than face charges of sexual abuse has grown into a diplomatic issue with international repercussions. North Korean and American diplomats remain intransigent over their conflicting definitions of diplomatic immunity, as the police wait to serve an arrest warrant. And now at stake are issues of international law being brought before a United Nations committee, the status of a group of North Korean diplomats stationed in Moscow waiting for visas to enter this country, and a letter accompanying the Moscow group, according to a North Korean diplomat, that was written by a United States Army private who entered North Korea last summer under mysterious circumstances. The incident began on Sept. 5, a Sunday afternoon. A 43-year-old woman said she had been attacked by an assailant she described as ''an Oriental-looking man'' while she was walking along a bridle path at Twin Lakes Reservoir in the Town of Eastchester in Westchester County.

International The MX missile was threatened as the House voted 245 to 176 to delete funds to produce the weapons in 1983. Fifty Republicans joined 195 Democrats in denying the funds for the $26 billion program to build 100 of the intercontinental weapons. Although the House vote was not the final Congressional action, it was a severe setback for President Reagan. (Page A1, Col. 6.) The Administration accused Moscow of trying to influence the Congressional debate over the MX missile with warnings that the Soviet Union would match any new missile produced by Washington. (D23:6.)

Governor Kean signed an executive order today that will cut all state aid programs and department budgets by 3 percent starting Jan. 1 to help close a projected $150 million deficit in the current state budget. At the same time, he said for the first time that he would sign a bill calling for a rise of 1 percentage point in the state Governor Carey ordered the New York Legislature to convene Monday to deal with fiscal problems. Page B1. sales tax if it was enacted by the State Legislature. The tax is now 5 percent.

The Sports People column on Saturday misidentified the fiancee of Duk Koo Kim, the South Korean boxer who was fatally injured in about last month. She is Lee Young Mi.

A sustained slowdown in air traffic growth in recent years, together with high fuel costs, has made a tougher approach to operating costs all but compulsory for the world's international airlines. Most have shed their old managements and brought in more cost-conscious executives who have made deep personnel cuts, sold off aircraft and challenged the old strategy of growth for growth's sake. ''These are the years of the accountant,'' said Rod Muddle, the manager of United States operations for British Airways. ''Financial discipline is primary.''

As part of a continuing acquisition campaign, American Brands Inc. will acquire Pinkerton's Inc., one of the biggest names in security services. Under an agreement announced by the two companies late Monday night, American Brands will pay $77.50 a share, or about $165 million, for all of the 2.15 million outstanding shares of Pinkerton's class A and class B stock. The Class A stock, the only stock with voting privileges, is not publicly traded. The class B stock, which is traded over the counter, has been below $60 this year, but in the last week it has been in the 70's. It was quoted yesterday at $73.50.