rince George's County could not have done a better job of maintaining desegregated schools in the face of massive racial change in the 1970s, a population specialist testified in U. S. District Court today.

Ending the fourth week of testimony in the trial of the NAACP suit charging that the county schools remain illegally segregated, demographer George Grier described his own computer analysis of the effect of Board of Education actions on racial balance since the court ordered desegregation in 1972.

He concluded that "there is no pattern at all of systematic manipulation to make black schools blacker."

Grier, a partner in a Washington demographic consulting firm retained as an expert witness by the school system, said his analysis showed that the schools were better integrated than the 116 individual census planning areas that make up Prince George's and credited an effort by the school board "to keep racial balance in those schools despite racial change."

The Prince George's NAACP contends, among other things, that school closings, administrative boundary changes and a 1980 revision to the original school busing plan has contributed to creating almost as many "racially identifiable" schools today as in 1972. Grier concluded that 51 percent of the changes made since 1973 increased desegregation, 40 percent increased segregation and 9 percent had no effect at all.

Grier said the effect of the board actions on desegregation, based on a statistical analysis, were random and thus could not be seen as intentional manipulation. NAACP lawyers maintain that the acts that increased racial concentration show direct contravention of the 1972 desegregation order issued by U.S. District Court Judge Frank A. Kaufman.

Kaufman, who is hearing the latest arguments in the case, heard five days of testimony this week from school official Jon Peterson on the details of virtually every change made within the schools between 1973 and 1981, with particular attention to the report of a citizens panel that resulted in removal of about 1,400 students from busing in 1980.

The Citizens Advisory Committee on Busing was instructed by the school board to study ways to reduce "unnecessary busing." Its report, adopted by the board, reassigned more than 4,000 students to schools closer to their homes. The overwhelming majority of the reassigned students were blacks that the committee felt could be withdrawn from the busing plan without what Peterson called a "significant" effect on the racial balance of the schools involved. Many were black students whose families had moved into formerly all-white areas only to be bused into predominantly black schools.

Grier's statistics showed that 47 percent of the changes made under the plan increased segregation--pushed the black percentage in the individual school away from the county average--while 40 percent helped desegregation.

Under repeated questioning, Peterson said that in several instances students could have been reassigned in ways that would have furthered desegregation, but he maintained that was not the advisory committee's mission.

Peterson said that while some overwhelmingly black schools were made blacker in the process, the number of students involved was often small. Moreover, he asked the court to consider the benefit to the black students whose bus rides were shortened or eliminated.