In the following gem the BLS explains how its jobs surveys might be impacted by firms which go out of business. Here’s why the Birth/Death model is something you can believe in!
…… units that have gone out of business generally do not report their data for the month in which they go out of business. There are two primary reasons. First, the CES is a voluntary survey and not all firms respond. Second, companies by definition have no employees once they are out of business, and there may be no one to report their data…..
http://www.bls.gov/opub/mlr/2006/05/art4full.pdf
