The SHRM LINE® data are collected through a survey of human resource professionals. Data are collected from two samples of approximately 500 HR professionals at manufacturing firms and 500 at service sector firms. Because the manufacturing sector is more cyclically sensitive than nonmanufacturing, changes in this sector are often leading indicators of change in the overall economy. Compared with overall employment, employment in the manufacturing sector tends to decline sooner during periods of economic contraction and increase sooner during periods of economic expansion. The service sector is widely viewed as an area where future job growth will occur and is monitored closely for that reason.
Two parallel LINE indices are released each month, one for manufacturing and one for the service sector. Each sample includes firms classified by their North American Industry Classification System (NAICS). Responses to the survey are weighted by Bureau of Labor Statistics (BLS) estimates of the percentage of the employment in each subsector.