>There is a concept from polling called a "random sample"... It's like taking a sample of a swimming pool, to check the chlorine levels.

And maybe the edge of the pool closest to the person taking the sample is the deep end where mostly adults swim, but if they walked a bit further and took the sample from the shallow side with the babies and toddlers they'd find out the water is actually 50% piss with more than trace amounts of feces mixed in as well.