[shkkmo]

> ie. Isnt this just a convenient excuse to deny that a survey is meaningful?

Nope, not at all.

It is true that no sample will ever be perfectly representative of a larger population. However, some samples can clearly be more representative than others and the easiest way to tell is to look at sampling methodology. Sample size has absolutely no effect on removing bias.

Here's some info so you can learn more about sampling methodologies: https://blog.socialcops.com/academy/resources/6-sampling-tec...

Now, doing actually representative samples is HARD in many situations, so is knowing how representative your sample is. This is why we can't predict things like who is going to win elections.