What factors do people actually base their career decisions on?

I've been doing a bit of digging around to find out what empirical evidence there is about the factors on which people base their career choices. 

There is quite a bit published on this topic, which I've sumarised below, but it's notable that pretty much every study gets its data by asking people what factors influenced their choices. This I think is problematic because it assumes a rational model of career decision making, in which people are fully aware of the basis of their choice. Decision making research, however, suggests otherwise, demonstrating time and again that people are not aware of the reasons for their choices.This indicates that we need to be very clear that the career research only tells us about the factors that people believe influenced their choices, rather than the information which actually did.

A further, although I think much less significant problem with the existing literature, is that much of the literature uses students studying vocational courses as participants - finding out why engineering students decided to choose engineering. You can see that the choice to study engineering might be linked to the choice to pursue engineering as a career, but the two are not the same.

That said, it is still quite interesting to understand that the factors that people think they base their decisions on, and the research gives a fairly broad account of this.

Rousseau and Venter (2009) summarise the research in a framework which highlights that there are three types of factors that are reported. First there are individual factors, which generally focus on career related interests, personality and skills. Second are environmental factors which are quite pragmatic and include the number of job opportunitites there are, the requirements of the job and the chances of professional development or promotion. The final group of factors are described as situational and these include things such as the educational level of the individual, and the influence of their family and friends.

There is empirical evidence that these factors are all perceived to have an influence on job choice, but they are not all equally prevalent in the literature. Abrahams et al. (2015) review the literature and found that the most prominent were family, academic potential, job opportunities, and socio cultural factors. In another review,
de Magalhaes and Wilde, 2015 concluded that money, job availability, job security and opportunities for advancement were the most important factors.

Paolillo and Estes (1982) asked engineers, accountants, doctors and lawyers to rate how important the following factors were to their job choice:

Earning potential
Association with people in that profesion
Parental influence
Cost of education
Social status attainment
Job satisfaction
Years of education required
Aptitude for subject
Teacher influence
Peer influence
Previous work experience
Availability of employment

Astonishly, they found that the two LEAST influential factors were job satisfaction and aptidude. This suggests that their participants felt that they were far more influenced by advice from others (parents, teachers and peers), the opportunities which came their way (previous experience and contacts) pragmatic factors (cost and time of training and availability) and extrinsic rewards (social status and earning potential).

Other more recent students support these relative weightings. Advice from others was shown by Chope, 2005; Dick and Rallis, 1991; Ferry, 2006; Jawirtz, & Case, 1998; Myburgh, 2005; potential for development  was shown by Abrahams et al., 2015 and Rousseau & Venter, 2009; and extrinsic rewards by Abrahams et al., 2015; Jawirtz, & Case, 1998 and Lanthan, Ostrowski & Pavlock, 1987. A few other factors have shown up occasionally. Instrinsic aspects of the job were shown by Mashige and Oduntan, 2011 and Palmer, Burket & Aubusson,2017, who identified values as important, skills were rated as important in a number of studies (Jawirtz, & Case, 1998; Rousseau and Venter, 2009) and Stephen and Makotose, 2007, found that their engineer participants were intrinsically motivated by their interest in the topic. Finally, Jawirtz & Case found that participants were influenced by their perceptions of the social identities of the occupation they were considering. 

Overall then, the literature suggests that people don't think their job choices are very influenced by their belief that they will enjoy or be good at the job. Instead, they are far more influenced by their belief in their ability to get the job, the views of their family and friends and their perceptions of their chances of objective career success (money and promotions).

References
Abrahams, F., Jano, R., & van Lill, B. (2015). Factors influencing the career choice of undergraduate students at a historically disadvantaged South African university. Industry and Higher Education, 29(3), 209-219.

Chope, R. C. (2005). Qualitatively assessing family influence in career decision making. Journal of Career Assessment, 13(4), 395-414.

Dick, T. P., & Rallis, S. F. (1991). Factors and influences on high school students' career choices. Journal for Research in Mathematics Education, 281-292.

de Magalhaes, J. R. A., & Wilde, H. (2015). An exploratory study of the career drivers of accounting students. Journal of Business & Economics Research (Online), 13(4), 155. 

Geiger, M. A., & Ogilby, S. M. (2000). The first course in accounting: students’ perceptions and their effect on the decision to major in accounting. Journal of Accounting Education, 18(2), 63-78.

Hackman, J. R., & Oldham, G. R. (1976). Motivation through the design of work: Test of a theory. Organizational behavior and human performance, 16(2), 250-279.

Humphrey, S. E., Nahrgang, J. D., & Morgeson, F. P. (2007). Integrating motivational, social, and contextual work design features: a meta-analytic summary and theoretical extension of the work design literature. The Journal of Applied Psychology, 92(5), 1332 - 1356.

Jawirtz, J., & Case, J. (1998). Exploring the reasons South African students give for studying engineering. International Journal of Engineering Education, 14(4), 235-240. 

Mashige, K. P., & Oduntan, O. A. (2011). Factors influencing South African optometry students in choosing their career and institution of learning. African Vision and Eye Health, 70(1), 21-28.

Paolillo, J. G., & Estes, R. W. (1982). An Empirical Analysis of Career Choice Factors Among Accountants, Attorneys, Engineers, and Physicians. THE ACCOUNTING REVIEW, 57(4).

Palmer, T. A., Burke, P. F., & Aubusson, P. (2017). Why school students choose and reject science: a study of the factors that students consider when selecting subjects. International Journal of Science Education, 39(6), 645-662.

Rousseau, G. G., & Venter, D. J. (2009). Investigating the importance of factors related to career choice. Management Dynamics: Journal of the Southern African Institute for Management Scientists, 18(3), 2-14.