[knodi123]

is it a smooth relationship, or is it more of a step function with 1 steps?

I always suspected that the reality was more like "people who are able to afford children and able to make long-term plans tend to have only as many children as they want, when they feel they are ready, but people who aren't able to afford children or who don't make long-term plans will tend to take a more devil-may-care attitude towards procreation."

[TeMPOraL]

From what I heard, in very poor countries children are often treated as investment. A child can start paying itself off by working as soon as even 5 years after being born. As a parent, you want someone to take care of you when you're old, and given high children mortality, you're better off making more of them in hope at least one survives to adulthood. Basically, those people are too poor to afford not having many children.

[JoeAltmaier]

This is rapidly becoming ancient history. There's a wonderful youtube video showing all the countries on earth, moving on a multimensional chart by infant mortality and standard of living. The origin is ideal. All countries but 1 or two have shot like arrows toward the origin over the last century.

[exch]

This talk by Hans Rosling may be what you are referring to.

https://www.youtube.com/watch?v=dymPP9RhPjw

[marcosdumay]

Across countries this is a very noisy cloud of points where, if you go out and calculate a regression it's pointing down. Like every other social variable.

Since population explosion has felt out of fashion, there's a long time that I didn't see such plot. But what I've seen has a much clearer tendency than most social correlations people use at real decisions. It's about as clear as most correlations of quality of life with GDP.