[jackweirdy]

My inner pessimist is expecting to see a "there was this Daily Mail article one time".

Everywhere I look, I see the opposite. Families with a comfortable amount of disposable income have the 2.4 kids, but those in poverty (and particularly the working poor) have 3, or upwards. Anecdotal, but I'm yet to see evidence to the contrary

[TeMPOraL]

There's evidence on a national scale that birthrate is anticorrelated with wealth. The better off people are on average, the less kids they have.

[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.

[Retric]

This is not true; on average richer men have more children.

If you try and slice it by family you find that the 'traditional' family makes up a fairly small percentage of the population.

[TeMPOraL]

This TED talk focuses on the anticorrelation I wrote about: http://www.ted.com/talks/hans_rosling_shows_the_best_stats_y....

[Retric]

Richer countries have lower birth rates.

Richer men in the same country have more kids.

PS: I think I just misread your comment. By "national scale" I thought you meant in the same country.

[TeMPOraL]

Ok, I think I should have written "international scale", I apologize for the confusion.

I don't know of any study on national level, i.e. of families in a single country. The only thing I know of are anecdotes and stories about very poor families having 5+ children.

[Retric]

I have seen this stat from a few studies.

EX: http://econlog.econlib.org/archives/2011/06/kids_are_normal....

Higher income > more kids, Higher education > fewer children.

This seems fairly obvious as people are less likely to have children and stay in school. But, as I understand it the effect is larger than that.

[exch]

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

A talk by Hans Rosling[1] on the subject.

[1]: https://en.wikipedia.org/wiki/Hans_Rosling