Land Measurement Bias: Comparisons from Global Positioning System, Self-Reports, and Remote Sensing Data

Abstract

We investigate the reliability of land measurement modes on non-classical measurement error and empirical relationships. In our multi-country survey experiment, we find significant differences between GPS and remotely sensed data only in Viet Nam, where plot sizes are small relative to the other countries. The magnitude of farmers’ self-reporting bias relative to GPS measures is nonlinear, with the largest magnitude of self-reporting bias of 130% of a standard deviation (2.2-hectare bias) in the Lao People’s Democratic Republic relative to Viet Nam, which has 13.3% of a standard deviation (.008-hectare bias). In all countries except Viet Nam, the inverse land size–productivity relationship is upwardly biased for lower land area self-reported measures relative to GPS measures. In Viet Nam, the intensive margin of organic fertilizer use is negatively biased (30.4 percentage points) by self-reported measurement error. We conclude by considering sources of measurement error in implementation and costs.

Keywords: Land measurement, Agriculture, Survey Methods, Remote Sensing

JEL Classification: Q24, Q15, O12, Q12, O13