Encyclopedia of Sociology

AGING AND THE LIFE COURSE

term. For example, financial security and ade-
quate supervision ameliorate most of the negative
effects of parental divorce on subsequent socioe-
conomic achievements and physical and mental
health (e.g., Kessler and Magee 1994). Second, two
of the primary mechanisms by which childhood
traumas generate poor health in later life are
socioeconomic achievement and high-quality so-
cial relationships (e.g., McLeod 1991). That is,
childhood traumas are often associated with lower
socioeconomic status and poor-quality relation-
ships during adulthood—both of which are risk
factors for physical and mental illness. If, however,
individuals who experienced childhood traumas
manage to achieve adequate financial resources
and supportive social ties during adulthood, their
excess risk of illness in middle and late life is
reduced substantially.

The Persisting Effects of Early Life Deci-
sions. There now is substantial evidence that the
decisions that individuals make during early adult-
hood have important consequences for their life
circumstances in late life. Studies of retirement
income provide perhaps the best illustration of
this research domain. The strongest predictor of
retirement income is occupational history. Through-
out adulthood, individuals ‘‘sort themselves’’ into
jobs that differ not only in income, but also in
benefits (i.e., total compensation packages). Of
these, the availability and quality of pensions is
most important for retirement income. There is
strong evidence that the provision of pensions
differs not only by occupation, but also by industri-
al sector (Quadagno 1988). Thus, when individu-
als make occupational choices—including job
changes throughout adulthood—they are inevita-
bly determining, in part, their retirement incomes.

Research on women’s retirement income has
broadened our understanding of the life-course
consequences of early decisions. Women and men
tend to be concentrated in different occupations
and different industrial sectors—and those in which
women dominate have, on average, lower earnings
and lower likelihood of pension coverage (O’Rand
1988). Moreover, family formation decisions strong-
ly affect women’s job histories. Compared to men,
women are less likely to work full-time and work
fewer total years, largely as a result of parental re-
sponsibilities. All of these factors combine to pro-
duce substantially lower retirement incomes for
women than for men (O’Rand and Landerman 1984).

LIFE-COURSE TRAJECTORIES AND

PERSON-CENTERED RESEARCH

The two research domains described above focus

on interindividual differences in late life and

intraindividual change over the life course. A third

domain, less developed than the others but excit-

ing in its scope, attempts to examine interindividual

differences and intraindividual change simultane-

ously. At this point, two emerging research tradi-

tions illustrate the nature and potential of this

approach.

Life-Course Trajectories. Trajectories refer

to long-term patterns of stability and change. They

can be examined at both the aggregate (e.g., the

‘‘typical’’ career, the modal pathway to nursing

home placement) and individual levels. Thus, tra-

jectories capture patterns of intraindividual change.

Examination of heterogeneity can be pursued in

two ways. In the first, the trajectory that best

describes the sample or population is constructed.

Subsequently, using techniques such as hierarchi-

cal linear modeling or growth-curve analysis, in-

vestigators can examine the extent to which fac-

tors of interest alter the shape of the trajectory.

For example, a trajectory of earnings across adult-

hood can be constructed for a given sample. Inves-

tigators can then examine the degree to which

factors such as sex, education, and race affect the

shape of the earnings trajectory. In the second

approach, multiple common trajectories are iden-

tified and investigators then determine the charac-

teristics associated with those trajectories. Using

this approach, for example, several common tra-

jectories of earnings during adulthood could be

identified (e.g., consistently increasing earnings,

earnings peaking during mid-life and then de-

creasing, consistently decreasing earnings, a rela-

tively flat earnings history). Factors such as sex,

education, and race could then be examined to

determine their association with these distinctive

earnings trajectories.

Trajectory-based research, with its focus on

both interindividual differences and intraindividual

change, is very attractive. The major limitation to

the use of this approach is the availability of data,

because longitudinal data covering long periods of

time are required if one wishes to understand life-

course patterns. It should be noted, however, that

trajectory-based research can also be useful for

studying shorter processes (e.g., patterns of illness