The SAUR report provides substate unemployment rates that have been seasonally adjusted by the Bureau of Business Research and contains seasonally adjusted rates for the nation, North Carolina, South Carolina, Tennessee, and Virginia. Seasonal adjustment, which is used in analyzing non-seasonal trends, is a statistical method for removing the seasonal component of a time series. The removal of seasonal fluctuations allows for a better understanding of the true movements of the economy's various components.
According to the U.S. Bureau of Labor Statistics (BLS), the levels of employment and unemployment (and other measures of labor market activity) often undergo regular fluctuations due to seasonal events. These events could include changes during major shopping periods (i.e., the Christmas season at a mall) or traditional vacation months (i.e., June to August at the beach). Because seasonal events follow a regular pattern each year and appear in most economic indicators, their influence on statistical trends can be eliminated by adjusting the statistics from month to month.
Much of the monthly data that is distributed by BLS and other government agencies is seasonally adjusted prior to public release. The unemployment rate is one major indicator - for the nation and states - that is regularly released after being seasonally adjusted. However, BLS and cooperating agencies do not seasonally adjust the data for substate areas. Thus, without also adjusting the substate data, it is difficult to make systematic and effective comparisons between monthly movements at the state level and in its substate areas.