The state and city of New York have lost their 7-year-old suit to force adjustment of 1980 census results to compensate for an alleged severe undercount of blacks and Hispanics.

The state and city sued the Census Bureau on Aug. 8, 1980, claiming that since New York had a large number of blacks and Hispanics, an undercount could cost the state a seat in the U.S. House.

The city claimed that since many federal grants are based on population, it would lose millions of dollars because of an undercount -- $26 million to $52 million a year, according to the latest city estimates.

Steven Obus, chief of the civil division of the U.S. attorney's office in New York, said in a telephone interview yesterday that federal Judge John Sprizzo on Tuesday ruled against the state and city request that the Census Bureau be required to adjust the 1980 census.

"The judge decided as a matter of fact that the Census Bureau's conclusion that it could not make an adequate adjustment was reasonable," Obus said.

"He agreed with the bureau that the statistical and demographic professions had not developed adequate methods" up to that time "for measuring the degree of completeness and accuracy" of the 1980 census.

Obus said the judge had stressed that while the bureau might have been able to make an adequate adjustment for New York, he agreed with the bureau's contention that it could not be sure of making an accurate adjustment for the whole country. In that case, New York might gain from an adjustment but other areas might lose unfairly, according to the judge's reasoning, Obus said.

Undercounting, however, remains as potential problem for 1990 census planners. Techniques of adjusting undercounts have been substantially improved, and some Census officials strongly believe that it would be possible to make an accurate nationwide adjustment by early 1991 for the purpose of reapportioning Congress and allowing the states to redraw state legislature district lines. Some officials also think it would be possible to obtain accurate population counts for cities, towns, counties, school and sewer and water districts or other small areas.

But other specialists disagree, and the Commerce Department announced Oct. 30 that it had decided against making an adjustment for any undercount in 1990. Rep. Mervyn Dymally (D-Calif.), chairman of the House subcommittee on the census, has introduced legislation to require a 1990 undercount adjustment, however. And New York and other jurisdictions are considering new lawsuits.

The Census Bureau has estimated that in the 1980 census, the undercount of the whole population was one percent to 2 percent but that for blacks and Hispanics it was 5 percent to 6 percent.