Longitudinal Research
Longitudinal research is a type of correlational research that
involves looking at variables over an extended period of time. This type of
study can take place over a period of weeks, months, or even years. In some
cases, longitudinal studies can last several decades.
How Longitudinal
Research Works
So why would
researchers want to conduct studies that take a very long time to complete? One
reason is that a longitudinal study can be used to discover relationships
between variables that are not
related to various background variables. This observational research technique
involves studying the same group of individuals over an extended period.Data is
first collected at the outset of the study, and may then be repeatedly gathered
throughout the length of the study. Doing this also allows researchers to
observe how variable may change over time (“What
is longitudinal study? - Definition from WhatIs.com,” n.d.).
Example.Imagine that a group
of researchers is interested in studying how exercise during middle age might
impact cognitive health as people age. The researchers hypothesize that people
who are more physically fit in their 40s and 50s will be less likely to
experience cognitive declines in their 70s and 80s.The researchers obtain a
group of participants who are in their mid-40s to early 50s. They collect data
related to how physically fit the participants are, how often they work out,
and how well they do on cognitive performance tests. Periodically over the
course of the study, the researchers collect the same date from the
participants to track activity levels and mental performance.
Characteristics
- They are observational in
nature
- They are a type of correlational research
- Longitudinal research is often
contrasted with cross-sectional research
- Longitudinal research involves
collecting data over an extended period, often years or even decades
- Cross-sectional
research involves
collecting data at a single point in time
Types of Longitudinal
Research
There are three major
types of longitudinal studies:
- Panel Study: Involves sampling a
cross-section of individuals.
- Cohort Study: Involves selecting a
group based on a specific event such as birth, geographic location or
historical experience.
- Retrospective Study: Involves looking to the
past by looking at historical information such as medical records.
The Benefits
So what are some of the reasons why a
scientist choose to conduct longitudinal research over other methods? For many
types of research, longitudinal studies provide unique insight that might not
be possible any other way.
The benefit of this
type of research is that it allows researchers to look at changes over time.
Because of this, longitudinal methods are particularly useful when studying
development and lifespan issues. Researchers can look at how certain
things may change at different points in life and explore some of the reasons
why these developmental shifts take place.
An example of how this
research can be used include longitudinal studies that look at how identical
twins reared together versus those reared apart differ on a variety of
variables. Researchers track these participants from childhood into adulthood
to look at how growing up in a different environment influences things such
as personality and achievement.
Since the participants
share these same genetics, it is assumed that
any differences are due to environmental factors. Researchers can then
look at what the participants have in common versus where they differ to see
which characteristics are more strongly influenced by either genetics or
experience.Because longitudinal studies take place over a period of years (or
even decades), they can be very useful when looking at changes in development
over time. Researchers can utilize this kind of research to establish a
sequence of events when looking at the aging process.
The Drawbacks
As with other types of psychology research, longitudinal studies
have both their strengths and weaknesses. There are some important advantages
to conducting longitudinal research, but there are also a number of drawbacks
that need to be considered.
Longitudinal Studies
Can Be Expensive .Longitudinal studies require enormous amounts of time and are often
quite expensive. Because of this, these studies often have only a small group
of subjects, which makes it difficult to apply the results to a larger
population. Another problem is that participants sometimes drop out of the
study, shrinking the sample size and decreasing the amount of data collected.
Participants Tend to
Drop Out Over Time.This tendency for some participants to be more likely to drop
out of a study is known as selective attrition. In our example
above, participants might drop out for a number of reasons. Some might move
away from the area while others simply lose the motivation
to participate. Others
might become housebound due to illness or age-related difficulties, and some
participants will pass away before the study is concluded.
In some cases, this
can lead to an attrition bias and influence the results of the longitudinal
study. If the final group no longer reflects the original representative sample, this attrition can
also threaten the validity of the
experiment. Validity refers to whether or not a test or experiment accurately
measures what it claims to measure. If the final group of participants is not a
representative sample, it is difficult to generalize the results to the rest of
the population.
The World’s
Longest-Running Longitudinal Study.The world's longest-running longitudinal study
is the Genetic Studies of Genius, which is today referred to as the Terman
Study of the Gifted. The study was originally started in 1921 by psychologist
Lewis Terman to investigate how highly intelligent
children developed into adulthood.
The study is still
going on today, although the original sample has understandably grown much
smaller. The study originally had over 1,000 participants, but that number had
dwindled to just 200 by 2003. Some of the participants included scientist Ancel
Keys and educational psychologist Lee Chronback. Researchers plan to continue
the study until the last participant either drops out or dies.
Conclusion
A longitudinal study
can provide a wealth of information on a topic. Such studies can be expensive, costly,
and difficult to carry out, but the information obtained from such research can
be very valuable.
Reference
· What is longitudinal study? - Definition from
WhatIs.com. (n.d.). Retrieved August 27, 2019, from
https://whatis.techtarget.com/definition/longitudinal-study
Created by
AkhilRaj
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