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  • Moylan, Heather  (1)
  • Murray, Siobhan  (1)
  • Washington, D.C. : World Bank Group, Development Economics, Development Data Group  (2)
  • 1
    Language: English
    Pages: 1 Online-Ressource (circa 29 Seiten) , Illustrationen
    Series Statement: Policy research working paper 8374
    Series Statement: World Bank E-Library Archive
    Series Statement: Policy research working paper
    Parallel Title: Erscheint auch als Lobell, David B Eyes in the Sky, Boots on the Ground: Assessing Satellite- and Ground-Based Approaches to Crop Yield Measurement and Analysis in Uganda
    Keywords: Mais ; Ernteertrag ; Satellitenkommunikation ; Kleinbauern ; Uganda ; Graue Literatur
    Abstract: Crop yields in smallholder systems are traditionally assessed using farmer-reported information in surveys, occasionally by crop cuts for a sub-section of a farmer's plot, and rarely using full-plot harvests. Accuracy and cost vary dramatically across methods. In parallel, satellite data is improving in terms of spatial, temporal, and spectral resolution needed to discern performance on smallholder plots. This study uses data from a survey experiment in Uganda, and evaluates the accuracy of Sentinel-2 imagery-based, remotely-sensed plot-level maize yields with respect to ground-based measures relying on farmer self-reporting, sub-plot crop cutting (CC), and full-plot crop cutting (FP). Remotely-sensed yields include two versions calibrated to FP and CC yields (calibrated), and an alternative based on crop model simulations, using no ground data (uncalibrated). On the ground, self-reported yields explained less than 1 percent of FP (and CC) yield variability, and while the average difference between CC and FP yields was not significant, CC yields captured one-quarter of FP yield variability. With satellite data, both calibrated and uncalibrated yields captured FP yield variability on pure stand plots similarly well, and both captured half of FP yield variability on pure stand plots above 0.10 hectare. The uncalibrated yields were consistently 1 ton per hectare higher than FP or CC yields, and the satellite-based yields were less well correlated with the ground-based measures on intercropped plots compared with pure stand ones. Importantly, regressions using CC, FP and remotely-sensed yields as dependent variables all produced very similar coefficients for yield response to production factors
    URL: Volltext  (Deutschlandweit zugänglich)
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  • 2
    Language: English
    Pages: 1 Online-Ressource (circa 36 Seiten) , Illustrationen
    Series Statement: Policy research working paper 8618
    Series Statement: World Bank E-Library Archive
    Series Statement: Policy research working paper
    Parallel Title: Erscheint auch als Kilic, Talip Root for the Tubers: Extended-Harvest Crop Production and Productivity Measurement in Surveys
    Keywords: Maniok ; Ernteertrag ; Landwirtschaft ; Produktivität ; Haushaltsstatistik ; Malawi ; Subsahara-Afrika ; Graue Literatur
    Abstract: To document the relative accuracy of methods for microdata collection on root and tuber crop production, an experiment was implemented in Malawi over a 12-month period, randomly assigning cassava-producing households to one of four approaches: daily diary-keeping, with semi-weekly supervision visits; daily diary-keeping, with semi-weekly supervisory phone calls; two six-month recall interviews, with six months in between; and a single 12-month recall interview. Lapses in diary-keeping can underestimate true production, albeit to a lesser degree compared to recall. And the comparisons between the diary variants and the variation in underestimation by recall period are unclear ex ante. The analysis reveals that compared to traditional diary-keeping, the household-level annual cassava production is 295 kilograms higher, on average, (and assumed as closer to the truth) under diary-keeping with phone calls. This effect corresponds to 28 percent of the average traditional diary-keeping production estimate. Although the difference between the estimates based on six-month recall and traditional diary-keeping is statistically insignificant, 12-month recall underestimates annual production, on average, by 516 kilograms and 221 kilograms, respectively, compared to diary-keeping with phone calls and traditional diary-keeping. While the recall-based approaches both underestimate true production, six-month recall does so to a lesser extent. The evidence additionally demonstrates likely gross overestimation in international and ministerial statistics on cassava yields in Malawi. For improved microdata on root and tuber crop production, the adoption of (i) diary-keeping with phone calls (particularly if deployed in a broader mobile phone-based survey) or (ii) six-month recall, as a second-best alternative, is recommended
    URL: Volltext  (Deutschlandweit zugänglich)
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