Longitudinal research is a method of research used to study the same variables over an extended period of time. It’s a form of correlational research, which means that the relationships between variables are examined without being controlled.
Read on to find out more about longitudinal research and tips for conducting your own longitudinal study!
How Does Longitudinal Research Work?
Longitudinal research works by repeatedly collecting real-time data on the same individuals over a long-term period. As a research method, it’s therefore especially useful for studies that aim to establish how variables and their relationships to each other may change over time, such as those related to medicine and economics.
In contrast, cross-sectional research establishes a snapshot of data from different individuals at a specific moment. Such research often provides information that can then be used as a basis for a longitudinal study. For example, if a cross-sectional study establishes that there is a link between aging and running in men but not in women, researchers may then choose to conduct a longitudinal study into the health effects running has on men over time.
While there aren’t any set rules for how long a longitudinal study should be, most studies typically last at least a year. There are some well-known examples of longitudinal research that have continued for decades, such as the Panel Study on Income Dynamics (PSID), which has been collecting data on 5,000 US families since 1968!
How to Approach Longitudinal Research
When approaching longitudinal research, you should consider your research objectives and decide which of the three main longitudinal study types you will be conducting:
Panel studies. These studies collect data on the same individuals over a period of time.
Cohort studies. Similar to panel studies, cohort studies involve collecting real-time data on a group of individuals selected for a shared experience, such as year of birth or involvement in an historic event.
Retrospective studies. These are studies that examine data from the past, such as individuals’ medical histories.
You will then need to decide whether you will collect your own data or rely on pre-collected data.
If you choose to collect your own data, you will have full control over the variables involved in the study. However, data collection can be expensive and time consuming, and it can be difficult to collect retrospective data accurately.
You may choose instead, then, to use pre-collected data. There are many centers and institutions that provide such data, including the US National Archives. The benefits of using pre-collected data are that it saves time, and you can usually trust the information provided. However, you may be restricted by the type of data you can access, as well as the variables chosen for analysis by the data collector.
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Longitudinal Research Pros and Cons
There are many unique benefits to conducting longitudinal research, which include:
● Being able to better understand cause-and-effect relationships between variables, as the timeline of events is preserved.
● Ensuring changes to variables are not caused by variations between one individual and another, as it is the same individual being observed each time.
● Eliminating the risk of recall bias in prospective studies.
However, longitudinal research isn’t suited to every study. In addition to being time-consuming, longitudinal research can also:
● Require significantly more resources than other methods of study.
● Suffer a common problem known as attrition, where participants in a study drop out for various reasons. This can lead to inconclusive or invalid results.
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