Occupational Outlook Handbook
Job openings result from the relationship between the population, labor force, and demand for goods and services with population restricting the size of the labor force–working individuals and those looking for work. And the size and productivity of the labor force limits the quantity of goods and services that can be produced.
In addition, changes in the demand for goods and services influence which industries expand or contract. Industries then respond by hiring the workers necessary to produce goods and provide services.
However, improvements to technology and productivity, changes in which occupations perform certain tasks, and changes to the supply of workers will all affect which occupations will be employed by those industries.
Examining past and present changes to these relationships in order to project future shifts is the foundation of the U. S. Department of Labor’s research. Remember that the research makes assumptions to produce projections, but does not guarantee that an occupation or career field will grow or pay as projected. Events like 9/11 and the Great Recession were not taken into account before those events, and future events will have the same impact of showing the projections were “educated guesses”.
Here’s a link to the Occupational Outlook Handbook’s Career Outlook webpages: http://www.bls.gov/ooh/]