Land Measurement Bias and Its Empirical Implications

This paper investigates how land size
measurements vary across three common land measurement
methods (farmer estimated, Global Positioning System (GPS),
and compass and rope), and the effect of land size
measurement error on the inverse farm size relationship and
input demand functions. The analysis utilizes plot-level
data from the second wave of the Nigeria General Household
Survey Panel, as well as a supplementary land validation
survey covering a subsample of General Household Survey
Panel plots. Using this data, both GPS and self-reported
farmer estimates can be compared with the gold standard
compass and rope measurements on the same plots. The
findings indicate that GPS measurements are more reliable
than farmer estimates, where self-reported measurement bias
leads to over-reporting land sizes of small plots and
under-reporting of large plots. The error observed across
land measurement methods is nonlinear and results in biased
estimates of the inverse land size relationship. Input
demand functions that rely on self-reported land measures
significantly underestimate the effect of land on input
utilization, including fertilizer and household labor.