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College of Letters and
Research Methodology in Adult Development and Aging
Steven Mendoza, Ph.D.,MSCP
Psychology Adjunct Professor
Chapter 5 Research Methodology in Adult
Development and Aging.
• The Psychology of adult development is a branch
of scientific psychology, and thus shares the
methodological concerns of the parent field.
• Adult development psychology uses the same
kinds of data, generated by the same procedures,
as do other fields of psychology.
• The formal experiment, the correlational study,
the use of survey methodology are as much in
evidence here as elsewhere.
• As is true for other areas of psychology,
researchers in this field often have trouble
finding an adequate control group, to which to
compare their experimental group---
• ---they have problems generalizing their results
beyond the particular individuals whom they
happened to observe, and they worry about
• Cross sectional designs compare several age
groups (Cohorts) at the same time.
• They yield data on age differences.
• Longitudinal designs compare the same cohort at
different times. They yield data on age
• There also are additional concerns, not always
faced in other branches of psychology, that relate
directly to the fact that in the developmental
sciences we not only describe static phenomenon.
• But most importantly are concerned with the
measurement of change over time. Finally, there
are special methodological problems in doing
research with older subjects.
• Longitudinal studies suffer from subjects loss,
practice effects, and historical changes that
• But, cross sectional studies are more prone to
confusion of age effects with differences between
• Cross sectional cont’d:
• Difference scores tend to be less reliable than
scores on single occasions; alternate methods,
require three, or more measurement points.
• A major research problem in adult development
is finding representative samples; white, middle-
class males are generally overrepresented in the
• but in advanced old age woman are
overrepresented in the research literature.
• Longitudinal studies also have the problem of
keeping the sample representative once it is
recruited; lower-class subjects, for example,
tend to drop out in disproportionate numbers.
• Sequential designs are complex combinations of
the simple cross-sectional, and longitudinal
• A cross-sectional consists of two, or more cross-
sectional studies run at different times.
• A longitudinal sequence consists of concurrent
longitudinal studies of two, or more cohorts.
• Schaie’s most efficient design includes both cross
sectional, and longitudinal sequence.
• Formed by retesting the subjects of an earlier
cross-sectional study while testing new subjects
in a new cross-sectional study.
• Analysis of the resulting data can be cohort-
sequential (cohort v. Age), cross-sequential
(cohort v. time of measurement).
• In repeated measures design the same subject
are tested at different times.
• Independent samples designs test new subjects
from the same cohort, instead of re-testing the
same subjects at different times.
• Many experiment Designs (quasi experiments)
may yield important insights and allow
researchers to examine alternative explanations
for a variety of aging phenomena.
• Age-comparative experiments compare groups of
subject of different ages to assess their
performance of some behavior in order to
determine if a particular factor explains the age
differences in behavior.
• Single age group intervention designs study a
group on whom longitudinal data is available, and
compare the effects of intervention on stable
individuals experiencing decline.
• Molar equivalence-molecular decomposition
experiments seek to discover how the older
person might compensate for declines in
performance in one area by enhance
performance in another area.
• In addition to concerns about reliability , validity,
and objectivity, several issues bear on the validity
of developmental research.
• Relationships between observables, such as test
performance and behavior, and latent constructs,
such as anxiety and intelligence, must be stable
across time to provide valid representation of
• The method of confirmatory factor analysis is
used to test the equivalence of these
relationships across time, or different age groups.
• The generalizability of research finding must also
be taken in to account.
• The extent to which research findings can be
broadly applied depends greatly on the
representativeness of the sample.
• It is also necessary to be aware of the
demographics, and health characteristics of
subjects in order to understand how finding
may be relevant to other populations.