That makes the methods used to compile an estimate of noncitizens crucial. A method that overestimates undocumented immigrants, for example, would hit states with large immigrant populations especially hard. That would be compounded if, as many predict, this year’s rushed census produces big undercounts of states’ total populations.
The bureau’s task force is studying how to compile an estimate of noncitizens using administrative records and other data. The memorandum asks the group to find ways to measure an array of characteristics of noncitizens that might be used to verify records, including whether they face deportation, have overstayed visas or face immigration hearings.
It also asks the bureau to study whether statistical methods could help determine a person’s status when records are of no help. One principal method, imputation, uses an algorithm to make an educated guess about the occupants of a household based on its neighbors.
The bureau imputes the characteristics of a small number of households in every census. Depending on the quality of records — and the method of imputation — a sizable share of the noncitizen estimate could be educated guesses.
Calculating reapportionment is a sensitive task for the bureau. It is generally given to a team of experts, insulated from senior managers and political appointees, who calculate the distribution of House seats on several computers run by different staff members. Only if all the results match are the figures sent to the White House.
The bureau does not have to calculate apportionment; it is required only to produce an accurate population count. But the agency has long done the apportionment calculation as a courtesy. “There’s a tradition of transparency when the numbers are handed off from the bureau,” one expert said. “It’s a norm, not a law.”
In a norm-busting administration, that is another thing for census experts to fret about.
“Having watched censuses for 50 years, there is no doubt in my mind that this is the most politicized census in my lifetime,” Bill O’Hare, a demographer and author of two books examining the accuracy of censuses, said on Wednesday. “There is a whole series of things that suggest this administration doesn’t see an accurate census count as very important.”