Yeah, there's an argument that using sample sizes that are too high is unnecessary/inefficient for research - as well as arguably unethical (and conversely, using sample sizes that are too small is considered unscientific and unethical). But there's a few things to consider when you need to determine the sample size of a survey: 1.) population size; 2.) the confidence interval (the margin of error you're allowing for in the survey - a lot of the time with surveys you see online it's a margin of error of + or - 5%); 3.) the confidence level (how confident you are that the actual mean of the results falls into the confidence level; 4.) the standard deviation (a lower standard deviation means the values will be clustered around the mean, a high standard deviation means they're spread across a wider range) - when you haven't yet run a survey, don't know what your standard deviation's going to be... .5 is what's used on a lot of surveys.
In statistics there's something called a z-score you use for formulas trying to take your confidence level and plug it into a formula to get the required sample size. For a 95% confidence level (with that +/- 5% margin of error I mentioned) the z-score = 1.96.
There's a few different formulas you can use to determine a sample size. One common one is Cochran's formula, which is:
necessary sample size = (z-score)2 x Standard deviation x (1-standard deviation) / (margin of error)2 , so plugging all that shite I talked mentioned above
necessary sample size = (1.96)2 x .5(.5) / (.05)2 ... (3.8416 x .25) / .0025.... .9604/.0025... 384.16
And since you can't sample .16 of a person, the necessary sample size is 385.
Then there's a correction formula for Cochran's formula for "small populations", which is:
adjusted necessary sample size = the necessary sample size we got above / 1 + (necessary sample size from above - 1)/size of population being sampled.
So filling in those variables with the Netherlands' population (which you'll see, we don't really need to do because the Netherlands does not have a small population)
adjusted sample size = 385 / 1+ (384/17.5m)... 385 / 1 + ( .00002194)... so 385/1.00002194... 384.991553
& since we can't sample .99 of a person, that's 385.
It's important to note that statistical significance is not always the same as research significance (though they can be related) and there are a lot of variables that go into whether a sampled population is considered quality or not.
Apologies for the random statistics lesson!