(Basically in A levels there's a branch called stats, that's what this is)

Population

This is basically our dataset.

EG: assume we want to know who the british population is gonna vote for in the next election. Everyone of voting age is our statistical "population"

How to represent the Population

Census

This is where u take the info from ALL of the population,

Very impractical, imagine asking everyone on who they'd vote for. A funnier example is Quality assurance in a pie factory, if u take a census on all the pies, ur gonna have to eat all of em, leaving nothing to sell

Sample

here You instead take a fair sample of ur population. So not everyone, just a few.

Methods of Sampling:

Random

You take like random ppl, it can be hella biased

Nth

EG: you knock on every 18th door.

opportunity (easiest)

this for the lazy asses, in context of the voting, u just ask all your friends

Quota [If it's categorised Data]

You take a limited amount from each Category.