Different governments have somewhat different methods of calculating their unemployment rate. The US, for example, has the US Bureau of Labor Statistics, and one of the things they do is send out a monthly survey to a range of households (currently about 60k households) and collect employment data from them. That’s considered a big enough sample size to get useful data about the overall unemployment rate.
https://www.bls.gov/cps/cps_htgm.htm
Latest Answers