To facilitate international comparisons, some organizations, such as the OECD, Eurostat, and International Labor Comparisons Program, adjust data on unemployment for comparability across countries. Though many people care about the number of unemployed individuals, economists typically focus on the unemployment rate, which corrects for the normal increase in the number of people employed caused by increases in population and increases in the labour force relative to the population.
That can impact non-industrialized economies, such as the United States and Europe in the early 19th century, since overall unemployment was approximately 3% because so many individuals were self-employed, independent farmers; however, non-agricultural unemployment was as high as 80%.Many economies industrialize and so experience increasing numbers of non-agricultural workers. For example, the United States non-agricultural labour force increased from 20% in 1800 to 50% in 1850 and  97% in 2000. The shift away from self-employment increases the percentage of the population that is included in unemployment rates. When unemployment rates between countries or time periods are compared, it is best to consider differences in their levels of industrialization and self-employment. Additionally, the measures of employment and unemployment may be "too high." In some countries, the availability of unemployment benefits can inflate statistics by giving an incentive to register as unemployed. People who do not seek work may choose to declare themselves unemployed to get benefits; people with undeclared paid occupations may try to get unemployment benefits in addition to the money that they earn from their work.However, in the United States, Canada, Mexico, Australia, Japan, and the European Union, unemployment is measured using a sample survey (akin to a Gallup poll). According to the BLS, a number of Eastern European nations have instituted labour force surveys as well. The sample survey has its own problems because the total number of workers in the economy is calculated based on a sample, rather than a census.