In shift share analysis, this reflects regional growth that can be attributed to positive trends in the specific industry or occupation at a national level. For example, nursing jobs might be growing in your region and that’s great. However, looking at the national trends for nursing jobs reveals that they’re growing most everywhere. In this case, your region isn’t necessarily “excelling” at providing nursing jobs; they’re doing well everywhere, and every region in the country will likely see some growth as a result.
See this longer article on shift share and its component parts.