"For example, if there are two different spellings of a surname, or an address was written down wrong, or the person moved, matching becomes significantly more complicated," he says.

There are others who charge the current administration is rejecting census readjustment for political reasons, because a statistical modification of population numbers may give the Democrats more power in the House, according to a graduate student working with Rubin.

But Vincent Barabba, former director of the Census Bureau under the Nixon, Ford and Carter Administrations says that adjusting undercounted groups is generally advisable--at least for future censuses.

"I would have suggested to them that they use the research but not use it until the [1990] census was over. They need to look at the figures before proposing an adjustment, but it should be a [permanent policy in the future]," Barabba says.

In the face of such arguments, however, the Reagan Administration continues to stand firmly against census modification, and whether or not the new research will ever be implemented remains a mystery to Rubin and his cohorts.

"The census bureau says it could not do it in 1980 because it didn't have the tools," Rubin says. "Now we have the technology, and it is just a question of the timing." Population Category  1950  1960  1970  1980 Total population  3.3  2.7  2.2  0.5-1.4 Male  3.8  3.3  3.1  N.A. Female  2.8  2.2  1.4  N.A. Legally resident population  N.A.  N.A.  N.A.  0.5 Male  N.A.  N.A.  N.A.  1.5 Female  N.A.  N.A.  N.A.  -0.4 Black population  9.7  8.0  7.6  5.3 Male  11.2  9.7  10.1  8.0 Female  8.2  6.3  5.3  2.7 White and other races population  2.5  2.1  1.5  -0.2 Male  2.8  2.5  2.1  0.6 Female  2.1  1.7  0.9  -0.9

NOTE: A minus sign indicates net overcount.

N.A. = not available; difference between total and legally resident population probably negligible (except for 1980).

Lower percentage assumes presence of 2 million undocumented aliens in the estimated population; upper percentage assumes presence of 4 million undocumented aliens. The census population used in calculating the total population rates is the actual count, including an estimated 2 million undocumented aliens that were counted.

Blacks and other nonwhites.

White only.

Net undercount rates by race and sex from demographic analysis, 1950 to 1980 decennial censuses (estimated population minus census population as a percentage of estimated population).