It is necessary to identify and evaluate changes in portfolios of skills associated with jobs, occupations, and individuals. Like portfolios containing stocks and bonds, portfolios of skills are subject to change over time in their individual components and in the volume of each component. A job taxonomy is needed that partitions jobs into sets that are equivalent in terms of the skills required. A similar taxonomy for individuals is needed to partition workers into groups with sets of embodied skills that are equivalent. Finally, one must also be able to convert functions required on the job to skills possessed by workers before one can meaningfully assess the strength of the fit between workers and jobs. To properly gauge shifting skill requirements, it is necessary to build on a greater understanding of shifts in technology and industry dynamics.

The proposed high-level taxonomy should be related to portfolios of skills, providing a vehicle for tracking shifts in skill requirements that is independent of changing preferences in job titles. For example, the high-level taxonomy category "software professionals" might include skills that range from simple programming tasks to sophisticated database design or other software development skills. Over time, some skills will diminish in importance as others become more important (see Chapter 3); it is important to track both the details of change and the gross numbers of computing professionals employed in hardware, software, and deployment.