The paper examines how hours constraints affect the decision to change
jobs and the patterns of hours-wage tradeoffs which result from job changes.
We analyze job mobility in a labor market in which work hours on a given job
are inflexible and it is costly for workers to locate and move to alternative
jobs. Costs of mobility and imperfect information about job offers will
prevent a worker from adjusting hours by costlessly moving to jobs which offer
wage—hours combinations on the his or her labor supply schedule.
Consequently, workers will trade off wage gains for hours adjustments in
making job changes. Specifically, we show that the partial effect of a
positive change in hours by job changers who were overemployed (underemployed)
on their prior job is to increase (reduce) the size of the wage gain required
to induce a quit. The partial effect of a positive change in hours by job
changers who are overemployed (underemployed) on their new job is to increase
(reduce) the size of the wage gain associated with the quit.
We test these propositions through an empirical study of the relationship
between the wage change and interactions among the change in hours and
indicators of overemployment and underemployment on the old job and the new
job. Despite the limitation imposed by small sample sizes and lack of
information on the magnitude of hours constraints, our results are supportive
of the theory.

If hours can be freely varied within jobs, the effect on hours of
changes in preferences for those who do change jobs should be similar to
the effect on hours for those who do not change jobs. Conversely, if
employers restrict hours choices, then changes in preferences should affect
hours more strongly when the job changes than when it does not change. For a
sample of married women we find that changes in many of the labor supply
preference variables produce much larger effects on hours when the job
changes.

The public believes that job security has deteriorated dramatically in the United
States. In this study, I examine job durations from eight supplements to the Current
Population Survey (CPS) administered between 1973 and 1993 in order to determine
if, in fact, there has been a systematic change in the likelihood of long-term
employment. In order to measure changes in the distribution of job durations, I
examine changes in selected quantiles (the median and the 0.9 quantile) of the
distribution of duration of jobs in progress. I also examine selected points in the
cumulative distribution function including the fraction of workers who have been with
their employer 1) less than one year, 2) more than ten years, and 3) more than twenty
years.
The central findings are clear. By the measures I examine, there has been no
systematic change in the overall distribution of job duration over the last two decades,
but the distribution of long-term jobs across the population has changed in two ways.
First, individuals, particularly men, with little education (less than twelve years) are
substantially less likely to be in long jobs today than they were twenty years ago.
Second, women with at least a high-school education are substantially more likely to
be in long jobs today than they were twenty years ago.