The other difference between the two sources is their method of firm size classification. SUSB uses the start period in classifying firm size for each individual firm and measures the difference in employment for each firm based on their end period employment minus their start period employment; this is often referred to as “start year sizing.” BED uses a firm’s start period size and classifies all employment changes at that size class until the firm changes into another size classification, even if this occurs during the period of analysis. BLS refers to this as “dynamic sizing.” .
