The undercounting of blacks in the U.S. Census is depriving them of equal representation, federal dollars and voting strength, the chairman of a House subcommittee studying the 1990 Census told the NAACP's western region convention.

Rep. Mervyn M. Dymally, D-Calif., told more than 200 convention delegates that constitutional and civil rights cannot be won until census undercounting, particularly among minorities, is corrected.The Western region of the National Association for the Advancement of Colored People, which includes nine Western states and Okinawa, Japan, met Friday and Saturday in the Ogden Hilton Hotel.

"The undercount represents a deprivation of constitutional proportions," said Dymally, who is the chairman of the Congressional Black Caucus and the Subcommittee on Census and Population.

Besides blacks, undercounting also affects illegal Hispanic immigrants and the homeless, he said.

Dymally said that since 1940, while the percentage of undercounting has dropped, the difference between undercounting of whites and blacks has remained at a constant 5.2 percent. In the 1980 census, 53 percent of the people missed were black.

"For certain segments of the black population, the undercount has reached critical levels. For example, the undercount of black males between the ages of 40 and 45 was 18.5 percent nearly one-fifth of this group," Dymally said.

Undercounting affects a decade of federal statistics, funding and congressional district apportionment.

The decennial census undercount causes the estimate of the number of black men who are unemployed to be set at less than it is actually is. "For every 85 black men reported as unemployed, there are another 15 not included in the publicly reported figures," he said.

The census figures are used to ensure compliance with the Voting Rights Act. States must ensure that minority voting strength is not diluted through gerrymandering. The census undercount makes the Voting Rights Act an "act of futility," Dymally said.

The Census Bureau needs to better use statistical procedures to calculate the undercount and make a correction, he said. The bureau already calculates the undercount, but does not use the data in a report to the president. Dymally wants it included, and has introduced a bill to do just that.

While the bureau supported the idea, Department of Commerce officials who govern the bureau have announced there will be no correction. The future of the bill, which is in a committee, looks bleak unless congressional leaders can be convinced to support it, Dymally said.

"The administration has weighed the gains and losses of a fight, laid down the gauntlet, and drawn the battle lines," Dymally said. He said Republicans believe the move to correct the figures would endanger many party-controlled congressional seats.

He encouraged the NAACP to adopt a stand for a fair census and to seek support for the passage of his bill.

He also commended the Census Bureau for attempting to be sensitive to the undercount issue, but said political appointees in the Department of Commerce and Office of Management and Budget have been irresponsible.