purpose of developmental research is to assess
changes over an extended period of time. For example, developmental research would be an ideal choice
to assess the differences in academic and social
development in low-income versus high-income
It is most common when working with children
as subjects for obvious reasons and can be
undertaken using several methods: longitudinal,
cross sectional, and cross sequential.
Longitudinal studies assess changes over an
extended period of time by looking at the same
groups of subjects for months or even years.
Looking at academic and social development,
we may choose a small sample from each of the low-
and high-income areas and assess them on various
measures every six months for a period of ten years.
The results of longitudinal studies can
provide valuable qualitative and quantitative data
regarding the differences in development between
major concern with longitudinal research, aside from
the obvious lack of control, randomization, and
standardization, is the length of time it takes to
complete the study.
Imagine starting a project that must be
constantly maintained for a period of ten or more
subject mortality rate due to illness, relocation,
and other factors alone could result in major
concerns, not to mention the amount of energy and
time that must be devoted to the research.
One way to reduce the amount of time and the
mortality rate in a developmental study is to assess
different ages at the same time rather than using
the same groups over an extended period.
A cross sectional study might look at the
same theory regarding academic and social
development but assess a small group of three year
olds, six year olds, nine year olds and 12 year olds
at the same time.
assumption is that the differences between the age
ranges represent natural development and that of a
longitudinal study had been used, similar results
would be found.
The obvious benefit is in the length of time
it takes to complete the study, but the assumptions
that the six year old group will achieve the same
academic and social development as the nine year old
group can be invalid.
Cross sequential studies combine both longitudinal
and cross sectional methods in an attempt to both
shorten the length of the research and minimize developmental
For this method, groups of different age children
(three, six, and nine for example) may be studied
for a period of three years to both assess developmental
changes and assure that the typical three year old
is similar to the typical 6 year old after three years