Ask an Economist:
What Are Smoothed Seasonally Adjusted Estimates?
Each month the Research & Planning (R&P) section of the Wyoming Department of Employment produces seasonally adjusted unemployment rates for the State of Wyoming in cooperation with the Bureau of Labor Statistics (BLS).
The BLS is replacing seasonally adjusted estimates with smoothed seasonally adjusted estimates starting with the publication of the January 2010 unemployment rates (Bureau of Labor Statistics). This is in response to state users who have voiced concerns about the month-to-month volatility in the official seasonally adjusted estimates. When statistically modeling a data series such as the seasonally adjusted unemployment rate, changes within an accepted range may occur. Changes that are not statistically significant don’t reflect any real underlying change, but this can be confusing to the average data user.
The smoothed seasonally adjusted estimates reduce the number of questionable turning points in the current estimate compared to the seasonally adjusted unemployment rate (see Figure). 
The smoothed seasonally adjusted methodology also improves the annual revision process by smoothing estimates between December and January, making the estimates more comparable (Bureau of Labor Statistics).
The BLS smoothes the estimates using the Henderson Trend Filter that suppresses irregular variation in the current month. According to the BLS, this filtering procedure, based on moving averages, removes irregular fluctuations from the seasonally adjusted series, leaving the trend (Bureau of Labor Statistics).
The entire series of seasonally adjusted estimates for Wyoming will be replaced from January 1976 through December 2009 and will be available at http://doe.state.wy.us/LMI/laus/toc.htm.
References
Bureau of Labor Statistics, (2010a). Smoothed Seasonally Adjusted Estimates (SSA) Questions and Answers. Retrieved March 8, 2010, from http://www.bls.gov/lau/lassaqa.htm
Bureau of Labor Statistics (2010b). Local Area Unemployment Statistics. Seasonal Adjustment. Retrieved March 8, 2010, from http://www.bls.gov/lau/lauseas.htm