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机器学习时代的贫困制图

Poverty mapping in the age of machine learning
Journal of Development Economics · 2024 · Paul Corral、Heath Henderson、Sandra Segovia

中文摘要

近年来,贫困制图方法取得了相当大的进展,其中大部分集中于将现代机器学习方法应用于遥感数据。采用这些方法生成的贫困地图通常使用一套共同的验证程序,通过将次国家层面的贫困估计值与基于调查的直接估计值进行比较,评估模型表现。尽管直接估计值是无偏的,但其对真实贫困率的度量可能并不精确,因此,这些验证程序是否能够反映模型的实际表现尚不明确。本文利用来自墨西哥的丰富数据集,以可信的真实值为参照评估现代贫困制图方法的表现,从而对该方法作出更严格的考察。我们发现,现代方法的表现不如作为基准的传统方法,这在很大程度上是因为遥感协变量的预测能力有限。我们还发现,在给定协变量集的情况下,机器学习产生的贫困估计值比传统方法的偏误更大,在最贫困的地理区域尤其如此。

Abstract

Recent years have witnessed considerable methodological advances in poverty mapping, much of which has focused on the application of modern machine-learning approaches to remotely-sensed data. Poverty maps produced with these methods generally share a common validation procedure, which assesses model performance by comparing sub-national poverty estimates with survey-based, direct estimates. While unbiased, direct estimates can be imprecise measures of true poverty rates, meaning that it is unclear whether these validation procedures are informative of actual model performance. In this paper, we use a rich dataset from Mexico to provide a more rigorous assessment of the modern approach to poverty mapping by evaluating its performance against a credible ground truth. We find that the modern method under-performs relative to benchmark traditional methods, largely because of the limited predictive capacity of remotely-sensed covariates. For a given covariate set, we also find that machine learning produces more biased poverty estimates than the traditional procedures, particularly for the poorest geographic areas.
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