というNBER論文が上がっている（ungated版へのリンクがある著者の一人のページ）原題は「When Your Bootstraps Are Not Enough: How Demand and Supply Interact to Generate Learning in Settings of Extreme Poverty」で、著者はAlex Eble（コロンビア大）、Maya Escueta（デューク大）。
以下はその要旨。
In settings of extreme poverty, how do demand and supply combine to produce child learning? In rural Gambia, caregivers with high aspirations for their children's future, measured before children start school, invest substantially more than others in children’s education. Despite this, essentially no children are literate or numerate three years later. When villages receive a highly impactful, teacher-focused supply-side intervention, however, children of high-aspirations caregivers are 25 percent more likely to achieve literacy and numeracy than others in the same village. We estimate patterns of substitutability and complementarity between demand and supply in generating learning that change with skill difficulty.
（拙訳）
極度の貧困という状況下で、どのように需要と供給が結び付いて子供の学習を生み出すのだろうか？ ガンビアの地方において、入学前のアンケート調査に基づく指標で自分たちの子供の将来に大望を抱いていることを示した養護者は、子供の教育に他者よりも顕著に多くの投資を行った。それにもかかわらず、3年後に読み書き計算ができた子供は事実上いなかった*1。しかし、教師に焦点を当てた非常に影響の大きい供給側の介入を村が受けた場合は、大望を抱く養護者の子供は、同じ村の他の子供たちよりも読み書き計算ができるようになる可能性が25%高かった。我々は技能の難しさとともに変わる、学習をもたらす需給の代替性と補完性のパターンを推定した*2。
*1:この点について本文では、標準偏差（SD）指標で0.28-0.30のプラスが観測されたものの、実態は短い単語が読めたり基本的な足し算ができるようになったに過ぎず、技能の習得という観点では事実上ゼロ、という評価を下し、次のように述べている：「This surprising result also illustrates the difficulty of using the SD metric to assess learning gains in settings where baseline learning levels are close to zero. In such settings, even a very small absolute change in test scores translates into a large relative gain. This increases the risk of erroneously positive conclusions about the importance of a given input.」
*2:本文では「We find patterns of complementarity and substitutability between demand and supply in producing these skills which change as skill difficulty increases. For the lowest-level reading and math skills, we find substitutability between aspirations (both educational and career) and educational supply. For higher level skills, we find evidence of complementarity between educational aspirations and educational supply. These results show that, in such settings, a large improvement in the quality of educational supply moves out the frontier from which families with high demand for education invest in their children, shifting the relationship between family demand and the child’s acquisition of foundational literacy and numeracy skills.」と記述している。
