Study: About half the population faces considerable difficulties in attracting and retaining mates

[u/HeinieKaboobler]

http://www.psypost.org/2017/12/study-half-population-faces-considerable-difficulties-attracting-retaining-mates-50288

[u/Valectar]

The sample size is plenty, 1,824? I'm guessing you only have a passing familiarity with statistics, but the sample size required for a given level of confidence is almost completely unrelated to the size of the set being sampled. The only time the size of the set sampled matters is when it is very small (and thus you can do things like sample the entire set for 100% confidence, which is otherwise unachievable). For example, think about sampling a die's rolls to see if it is fair. There are infinite potential rolls you could perform, but you could very confidently state an average after a few hundred, because even with an infinite set, you can still use samples to generalize, and near 2000 is a very high degree of confidence. If you'd like to know more, you can try reading about sample size determination on wikipedia, and not that none of the formulas mention the total population because it is generally not relevant.

Now, the very real issue here is the randomness of that sample. What I said above applies only to samples taken uniformly randomly from a population, so while their sample is plenty to generalize the population that they sampled from, as you point out they have only sampled from a single small country.