Have people made estimates of how cost-effective these are?
Yes, they did. In real world, “Plus” option means “one more person born in a middle-income country, in a poor and uneducated family”. And even that is expensive.
That might be the most cost-effective Plus option, actually—if you crudely model the cost of one extra birth as proportional to the child’s future income, then diminishing marginal utility of income means that it’s better to promote births in poorer countries (up to a point). The optimal income level at which to do a Plus intervention (in terms of maximizing the cost-effectiveness of Plus+Minus) depends on the cost of preventing a birth in a poor country. If the cost is high, you’d want Plus to be in a richer country due to the “overhead” of the Minus intervention, but if Minus costs almost nothing, you’d want Plus to be in a country only slightly richer than the Minus country.
Yes, they did. In real world, “Plus” option means “one more person born in a middle-income country, in a poor and uneducated family”. And even that is expensive.
That might be the most cost-effective Plus option, actually—if you crudely model the cost of one extra birth as proportional to the child’s future income, then diminishing marginal utility of income means that it’s better to promote births in poorer countries (up to a point). The optimal income level at which to do a Plus intervention (in terms of maximizing the cost-effectiveness of Plus+Minus) depends on the cost of preventing a birth in a poor country. If the cost is high, you’d want Plus to be in a richer country due to the “overhead” of the Minus intervention, but if Minus costs almost nothing, you’d want Plus to be in a country only slightly richer than the Minus country.