Dealing with selection bias in agricultural land area measurement using global position
Kilic, Talap et al.
Land area measurement is one of the fundamental components of agricultural statistics. Although agricultural statisticians have in the past relied on the tools of land surveyors (e.g. rope and compass) to accurately measure land areas, these methods are usually not cost-effective to adopt as part of large household and farm survey operations. As a result, national surveys have traditionally relied on farmerss own, potentially error-prone, assessments to record land area measurements that in turn inform a wide array of key agricultural statistics and analyses. However, the availability of affordable and more reliable handheld global positioning system (GPS) units has recently made GPS-based land area measurement a practical alternative. The increasing reliance on GPS-based land area measurement as part of household and farm surveys worldwide is also fueled by empirical evidence on the improvements in area estimates vis a vis farmer-reported assessments (Carletto et al, 2010; Dorward and Chirwa, 2010; Keita and Carfagna, 2009). While the use of GPS-based land area measurement is certainly the way of the future, in these relatively early stages of its application to survey work it is important to assess its advantages over other methods, and the possible issues with its use particularly in the context of low income countries where numeracy of respondents is limited, scores of "non-standardd land area measurement units are common place, cadastral records are non-existent, and the financial and human resources of national statistical offices are severely limited. Despite the increasing evidence on the benefits of using GSP devices in the context of household surveys in Africa (Dorward and Chirwa, 2010), concerns also remain in relation to the precision of such devices when measuring very small plots (Keita and Carfagna, 2009).
Event: Annual World Bank Conference on Land and Poverty 2013
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