[megous]

Available jobs increase with population. Additional people need more services, goods, etc. This leads to increased demand. In other words, more people are needed to produce stuff for more people.

[eksu]

Required jobs scale very very poorly with population. I wouldn't be surprised if the rate was something less than 1 additional person in the workforce for every 10 additional people in the population.

[fulafel]

That would mean that countries with larger populations would have higher unemployment rates, but that is not the case.

[finance-geek]

It would mean that any poor country could simply become wealthy by allowing unlimited immigration...Most poor countries are nicer relative to some worse-off country, so certainly there would not be a shortage of immigrants wanting to migrate.

[fulafel]

I think the null hypothesis has to be that there is no correlation between population size and employment.

[rorykoehler]

*in the 20th century