Source of economic data on unemployment is the Current Population Survey and the history behind it
Because unemployment insurance records relate only to people who have applied for such benefits, and since it is impractical to count every unemployed person each month, the government conducts a monthly survey called the Current Population Survey (CPS) to measure the extent of unemployment in the country. The CPS has been conducted in the United States every month since 1940, when it began as a Work Projects Administration program. In 1942, the U.S. Census Bureau took over responsibility for the CPS. The survey has been expanded and modified several times since then. In 1994, for instance, the CPS underwent a major redesign in order to computerize the interview process as well as to obtain more comprehensive and relevant information.
There are about 60,000 eligible households in the sample for this survey. This translates into approximately 110,000 individuals each month, a large sample compared to public opinion surveys, which usually cover fewer than 2,000 people. The CPS sample is selected so as to be representative of the entire population of the United States. In order to select the sample, all of the counties and independent cities in the country first are grouped into approximately 2,000 geographic areas (sampling units). The Census Bureau then designs and selects a sample of about 800 of these geographic areas to represent each state and the District of Columbia. The sample is a state-based design and reflects urban and rural areas, different types of industrial and farming areas, and the major geographic divisions of each state.
The total unemployment figures cover more than the number of people who have lost jobs. They include people who have quit their jobs to look for other employment, workers whose temporary jobs have ended, individuals looking for their first job, and experienced workers looking for jobs after an absence from the labor force (for example, stay-at-home parents who return to the labor force after their children have entered school). Information also is collected for the unemployed on the industry and occupation of the last job they held (if applicable), how long they have been looking for work, their reason for being jobless (for example, did they lose or quit their job), and their job search methods.