The Fifth Cell

One form of error that can affect census adjustments is correlation bias, reflecting people who are doubly missing—from the census and from the adjusted counts as well. This article presents a method for estimating the total national number of doubly-missing people and their distribution by race and sex. Application to the 1990 U.S. census adjustment leads to an estimate of 3 million doubly-missing people. Correlation bias is likely to be a serious problem for census adjustment in 2000. The methods of this article are well suited for measuring its magnitude.