"If a $100 increase in annual child tax benefits could increase fertility by 3.2 to 6.5 percent, should we have expected a 32 to 65 percent increase in the US fertility rate in response to the $1,000 Child Tax Credit, holding all other factors constant?
It wasn't a rhetorical question - and note carefully that last clause: "holding all other factors constant." Whittington, Alm and and Peters said fertility rate depended on annual child tax benefits AND several other factors; changes in those other factors could easily reduce or cancel the effect of increased annual child tax benefits.
By the way, that paper analyzes an additional 20 years of data and goes on to conclude that the original paper doesn't really hold up.
They also note other studies whose results were in line with Whittington, Alm and and Peters, and conclude a "lack of agreement in the literature" while not claiming to themselves be the last word.
It looks like my statement that "We can make it [greatly increasing the birth rate of native Americans] happen" through an increase in annual child tax benefits was too strong; the jury is out. But I never meant to imply that such an increase is ALL we'd need to do ... and an increase in annual child tax benefits is a good in its own right anyway; if there aren't more kids, then there are more child-raising resources at parents' disposal. I certainly don't accept that the only answer is to admit millions coming in search of a handout, or a job they're only pretending to be qualified for.
Your analysis posits that a $10/month net increase in income is going to cause some significant number of people to have children who otherwise wouldn't. Does that really give you the confidence to say we can greatly increase the birth rate via tax policy?
Of course - why wouldn't it?
Because a child tax credit that was almost 10 times larger didn't seem to budge it.