scaled to purge selection bias.<sup>33</sup> In other words, simply allowing one member of a Bangladeshi household to work in the US for _one month_ (for a gain of US$835 in present value) brings a larger increase in earnings to that household than a _lifetime_ of microcredit (for a gain of US$683 in present value).

Harrison and Scorse (2004) find that international anti-sweatshop campaigns against textile, footwear, and apparel plants in Indonesia caused a 20-25% increase in real wages for workers at foreign-owned and export-focused plants between 1990 and 1996. This translates to an annual wage gain of US$647 at purchasing power parity, which at a 10% discount rate has a present value of about US$6960. This is 58% of the _annual_ wage gain from working in the US.<sup>34</sup> In other words, the cumulative lifetime effect of the antisweatshop movement on an Indonesian worker’s earnings could be earned if that person had the chance to work in the US once for a period of about 30 weeks.

In the country in our sample whose wage ratio is closest to the median, Bolivia, the coefficient on years of education in a simple Mincer regression for Bolivian residents is 0.061. Since the average annual wage for Bolivian residents in our sample is US$3371 at purchasing power parity, this suggests that an additional year of schooling is associated with an annual wage gain of US$205. The net present value of a lifetime of such additional payments is about US$2250,<sup>35</sup> which is about 21% of the annual wage gain to a Bolivian working in the US.<sup>36</sup> But the ability of many interventions to achieve even one year of increased education is circumscribed. Kremer and Miguel (2004) (p. 206), find that medicating children to eliminate hookworm, roundworm, and other helminthic parasites is “by far the most costeffective method of improving school participation among a series of educational interventions” attempted in Busia, Kenya that underwent randomized evaluations. They find that deworming raised the present value of lifetime wages for a treated child by US$30, or US$71 at purchasing power parity.<sup>37</sup> This lifetime quantity is equal to about 0.6% of the annual gain to a Kenyan’s wages simply from working in the US.<sup>38</sup>

> 33 _Ro_ from Table 2, column 1 is 4.92, thus _Re_ is roughly 3.28 and the annual dollar gain for an equal productivity worker willing to move is $10,021.

> 34 They identify the effect by comparing textile, footwear, and apparel firms (the targets of the campaign) to other firms that were not targeted. The 20-25% real wage gain (p. 21 and Table 1B) is from a base mean 1990 wage of Rp1775000 for foreign firms and Rp1462000 for exporting firms. We use the former of the two to be conservative, so that a 25% gain constitutes Rp444000 per year, or US$647 at PPP, using the 1991 PPP conversation factor from World Bank (2007) of 685.78. The annual gain to an Indonesian male from working in the US is roughly US$11981 ( _Ro_ = 5.82 in gives the dollar gain of $17971 in Table 2, and scaling by _Re_ = _Ro_ /1.5 = 3.88 gives US$11981). The present value of $6960 includes a payment in year zero.

> 35 This is not the “return” to schooling, as Heckman, Lochner, and Todd (2006) stress; it does not account for costs of the education investment, most notably the opportunity cost of time. Strictly speaking, by the assumptions underlying the Mincer model the marginal return to schooling is zero, since individuals acquire education until the benefit equals the opportunity cost.

> 36 The present value is calculated at a discount rate of 10%, including a payment at time zero. The gain to a Bolivian migrant in Table 2 is US$16458 at PPP. Dividing this by 1.5 to adjust for selection bias gives approximately US$11000.

> 37 World Bank (2007) gives the PPP exchange rate to official exchange rate ratio as 0.42 for Kenya in 1999.

> 38 Kenya is not in our sample, but six low-income sub-Saharan African countries are, and here we use the lowest wage gain from among those: Ethiopia, whose wage gain is slightly lower than that of Uganda, a country that might be considered more comparable to Kenya. The wage gain to an Ethiopian from Table 2 is US$17,308 which, divided by

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