According to the Occupational Outlook Handbook, published by the Bureau of Labor Statistics (www.bls.gov/ooh/), what are the employment prospects of any chosen profession? What factors will create jobs (or decrease the number of jobs) in the field?

You can use the Bureau of Labor Statistics site to find the outlook for the occupation you choose. For example, if you choose to be an Athletic Trainer (under healthcare jobs), you can find information at https://www.bls.gov/ooh/healthcare/athletic-trainers.htm. There, you can find the average pay and the job outlook for this profession for the next decade or so. The profession of working as an athletic trainer is expected to grow by 23% from 2016-2016 (look under "Job Outlook"). This is much faster than average for all professions. The site will provide you with a comparison of your chosen profession's outlook, compared to that of all other jobs.
Under the link "Job Outlook," you can find more information about how and why your chosen profession might grow and a chart comparing the growth in this profession to the average growth of all professions (7%) and to professions in the healthcare field (12%). Athletic trainers, for example, are expected to grow in numbers because people are much more aware of the effect of sports-related injuries. In addition, more and more people are trying to stay active into their older years, resulting in more sports-related injuries. In some states, insurance companies will reimburse athletic trainers for their work.
https://www.bls.gov/ooh/healthcare/athletic-trainers.htm