Your questions are answered in great detail in the link at the bottom of the BLS page: https://www.bls.gov/opub/mlr/2008/12/art1full.pdf https://www.bls.gov/opu

Your questions are answered in great detail in the link at the bottom of the BLS page: https://www.bls.gov/opub/mlr/2008/12/art1full.pdf https://www.bls.gov/opub/mlr/2008/12/art1full.pdf