The authors discuss the alternative statistical methodologies that the BLS considered for creating size class tabulations from the Business Employment Dynamics data. The primary focus is on four methodologies: quarterly base-sizing, annual base-sizing, mean-sizing, and dynamic-sizing. They discuss the evaluation criteria that BLS considered for choosing its official size class methodology.
Link
http://econpapers.repec.org/scripts/redir.pl?u=http%3A%2F%2Fwww.bls.gov%2Fore%2Fpdf%2Fec050110.pdf;h=repec:bls:wpaper:ec050110