TECHNICAL NOTE The major work stoppages series dates back to 1947. The term "major work stoppage" includes both worker-initiated strikes and employer-initiated lockouts that involve 1,000 workers or more and lasting at least one shift. BLS does not distinguish between lockouts and strikes in its statistics. Information on work stoppages is obtained from reports from the Federal Mediation and Conciliation Service, State labor market information offices, BLS Strike Reports from the Office of Employment and Unemployment Statistics, and from major media sources. One or both parties involved in the work stoppage (employer or union) is contacted to verify the duration and number of workers idled by the stoppage. Days of idleness is calculated by multiplying the number of workers involved in the strike or lockout by the number of days workers are off the job. The number of working days lost for every major work stoppage is based on a 5-day workweek (Monday through Friday), excluding Federal holidays. Monthly major work stoppages data The Bureau of Labor Statistics compiles detailed monthly statistics on major work stoppages at http://www.bls.gov/wsp. Detailed data for each major work stoppage since 1993 includes the organization involved, location, beginning and ending work stoppage dates, the number of workers, and days idle. Monthly time series data since 1981 have been published (http://data.bls.gov/cgi-bin/surveymost?ws) for the following tables: * Number of work stoppages involving 1,000 workers or more beginning in the period * Number of work stoppages involving 1,000 workers or more in effect in the period * Number of workers involved in work stoppages beginning in the period * Number of workers involved in work stoppages in effect in the period * Days of idleness resulting from work stoppages in effect in the period * Days of idleness resulting from work stoppages in effect in the period, as a percent of estimated working time Major work stoppages detailed information and measures For more information on Work Stoppages methods and measures, see "Chapter 8. National Compensation Measures" of the BLS Handbook of Methods at: www.bls.gov/opub/hom/pdf/homch8.pdf.