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Abstract
The 2002 Census of Agriculture adjusted for whole-farm nonresponse by
dividing the potential farms on its list into size classes and then weighting the
respondents within each class to account for the nonrespondents.
Unfortunately, to assign the size-class memberships, a consistent measure
of size was needed for all potential farms not just census respondents.
Subsequently-collected census information sometimes contradicts these
class assignments. By defining indicator variables for census respondents
based on “corrected” class assignments, instrumental-variable calibration
can be used to construct an alternative set of nonresponse weights.
Assuming the response model underpinning these new weights is correct,
the bias from using the original set of nonresponse weights can be assessed.
The potential bias in the estimated farm count is caused by nonfarms on the
list being more likely to respond to the census than farms.