1 Answer | Add Yours
[You question was edited to accord with the eNotes policy that allows one question to be asked and answered per post. You may repost the others as separate Questions.]
All populations have natural variation. If a population study is done and only a small sample was selected then all the variations might not be accounted for in the results. Also, a randomly selected sample is best to ensure that all variations have equal opportunity to be accounted for in the sample.
We’ve answered 318,911 questions. We can answer yours, too.Ask a question