In particular, the National Bureau of Economic Research does not use the unemployment rate but prefers various employment rates to date recessions. Labor force participation rate
The labor force participation rate is the ratio between the labor force and the overall size of their cohort (national population of the same age range). In the West, during the later half of the 20th century, the labor force participation rate increased significantly because of an increase in the number of women entering the workplace. In the United States, there have been four significant stages of womens participation in the labour force: increases in the 20th century and decreases in the 21st century. Male labor force participation decreased from 1953 to 2013. Since October 2013, men have been increasingly joining the labour force. From the late 19th century to the 1920s, very few women worked outside the home. They were young single women who typically withdrew from the labor force at marriage unless family needed two incomes. Such women worked primarily in the textile manufacturing industry or as domestic workers. That profession empowered women and allowed them to earn a living wage. At times, they were a financial help to their families. Between 1930 and 1950, female labor force participation increased primarily because of the increased demand for office workers, womens participation in the high school movement, and electrification, which reduced the time that was spent on household chores.
The unemployment rate is expressed as a percentage and calculated as follows:

  
    
      
        
          Unemployment rate
        
        =
        
          
            Unemployed workers
            Total labor force
          
        
        ×
        100
      
    
    {\displaystyle {\text{Unemployment rate}}={\frac {\text{Unemployed workers}}{\text{Total labor force}}}\times 100}
  As defined by the International Labour Organization, "unemployed workers" are those who are currently not working but are willing and able to work for pay, currently available to work, and have actively searched for work. Individuals who are actively seeking job placement must make the effort to be in contact with an employer, have job interviews, contact job placement agencies, send out resumes, submit applications, respond to advertisements, or some other means of active job searching within the prior four weeks. Simply looking at advertisements and not responding will not count as actively seeking job placement.