From the vantage point of economics, unemployment exists whenever a potential worker has "time for sale" at the going wage rates, but no buyer/employer has yet offered a position that absorbs all the worker's surplus time and effort. Thus, ideally, unemployment rates would measure such surpluses of labor as a proportion of the total labor available at prevailing wage rates. For example, if households would willingly supply 10 percent more labor time and effort than firms currently hire, the unemployment rate is, conceptually, 10 percent. If, however, every worker worked exactly 90 percent as much as he or she would like, the official unemployment rate would be zero—all people who want work would have jobs, so no one would not be counted as unemployed.
This type of uncounted unemployment may be especially pronounced among part-time workers. Large numbers of people, including a lot of full-time students and homemakers with school-aged children, truly want to work only part time. In many cases, however, workers who have been laid off take part-time jobs as a "holding action" to keep food on the table and a roof overhead. Continuing waves of restructuring (down-sizing) in corporate America have clobbered large numbers of mid-level professionals and managers, many of whom lost jobs they secured only after several promotions during decades of work with an established firm. An increasingly common pattern is for these individuals to operate as "consultants" from their home offices or to work part time (e.g., filling out tax forms for H&R Block at $5 per hour during the tax season) while desperately seeking jobs comparable to those they have lost. Too frequently, however, these people ultimately find full time employment at salaries of only 40-60 percent of what they earned in their previous positions.
A related problem is that some people with full-time jobs supplement their income with a part-time "after-hours" second job. If they lose their part-time jobs, their "idle" time is not counted as unemployment. All of these people who would like to work more, but who are currently working either part-time or 40 hours per week, are not counted as "partially unemployed" by the Bureau of Labor Statistics.
The prevalence of part-time employment has grown over the decades, and the number of part-timers who would like full-time jobs appears to be growing even faster. Therefore, statistics for total unemployment rates may not be comparable across time. In 1994, the BLS revised its monthly questionnaire to more accurately track the numbers of part-time workers who want full-time jobs. Nevertheless, official unemployment rates remain unadjusted for part-time unemployment.