17 Longitudinal Study Advantages and Disadvantages

Longitudinal studies are a research design which requires repeated observations of the same variables over specific time periods. These may be shorter examinations or designed to collect long-term data. Under most situations, it is treated as a type of observational study, although there are times when researchers can structure them as more of a randomized experiment.

Most longitudinal studies are used in either clinical psychology or social-personality observations. They are useful when observing the rapid fluctuations of emotion, thoughts, or behaviors between two specific baseline points. Some researchers use them to study life events, compare generational behaviors, or review developmental trends across individual lifetimes.

When they are observational, then longitudinal studies are able to observe the world without manipulating it in any way. That means they may have less power to detect casual relationships that may form in their observed subjects. Because there are repeated observations performed at the individual level with this option, there is also more power than other studies to remove time-invariant differences while review the temporal order of events that occur.

The longest-running longitudinal study in the world today was started in 1921 by psychologist Lewis Terman. He wanted to investigate how highly intelligent children would develop as they turned into adults. The original study had over 1,000 participants, but that figure has dropped to under 200. Researchers plan to continue their work until there are no participants left.

These are the crucial longitudinal studies pros and cons to review before setting up this form of a panel study.

List of the Pros of Longitudinal Studies

1. This form of research is designed to be more flexible than other options.
There are times when a longitudinal study will look at one specific data point only when researchers begin observing their subjects. You will also find that this option provides enough data when implemented to provide information on unanticipated relationships or patterns that may be meaningful in specific environments. Since most of these studies are not designed to be lengthy, there are more options to pursue tangents here than in other research formats.

Researchers have an opportunity to pursue additional data points which were collected to determine if a shift in focus is necessary to review a complete set of information. If there is something interesting found in the material, then longitudinal studies allow for an option to pursue them.

2. The accuracy rate of the data collected during longitudinal studies is high.
When researchers decide to follow longitudinal studies to collect observational data, then the accurate rate of the information they collect is high because everything occurs in a real-time situation. Although mistakes do happen because no one is perfect, the structure and foundation of this option limits the problems that can occur. This information is also useful in the implementation of changes that may be necessary to achieve the best possible outcome during an observational period.’


3. This research method can identify unique developmental trends.
When researchers pursue a short-term longitudinal study, then they are looking for answers to very specific questions. If a long-term model is developed, there is an opportunity to identify specific developmental trends that occur in various fields, including sociology, psychology, and general medicine.

Researchers using longitudinal studies have opportunities to track multiple generations in specific family groups while still collecting real-time data on all of the individuals being tracked to see how current decisions can influence future outcomes for some population demographics.

4. It allows for the consistent use of the observational method.
It is a simpler process to collect information when using longitudinal studies for research because it almost always uses the observational method. This structure makes it possible to collect consistent data samples at the individual level instead of relying on extrapolation or other methods of personal identification. It is the consistency offered in this approach which provides for exclusion differences for individuals, making it possible to exclude variations that could adversely impact outcomes as it happens with other research options.

5. Longitudinal studies allow for unique a specific data points to be collected.
Most research study options provide a structure where data is available over a short time period for collection, offering a small window where cause-and-effect examples can be observed. Longitudinal studies provide an option to increase the amount of time provided for researchers to collect their data, sometimes on a very dramatic scale. There are some studies which are measured in decades or centuries instead of days, weeks, or months. This process makes it possible to examine the macro- and micro-changes that can occur in the various fields of humanity.

6. This process allows for higher levels of research validity.
For any research project to be successful, there are laws, regulations, and rules that must be instituted from the very beginning to ensure all researchers follow the same path of data collection. This structure makes it possible of multiple people to collect similar information from unique individuals because everyone is following the same set of processes. It creates a result that offers higher levels of validity because it is a simpler process to verify the data that is being developed from the direct observations of others.

7. There are three different types of longitudinal studies available for use.
Researchers have access to three significant types of longitudinal studies to collect the information that they require. Panel studies are the first option, and they involve a sampling of a cross-section of individuals. Cohort studies are the second type, which involves the selection of a group based on specific events, such as their historical experience, household location, or place of birth.

The final option is called a retrospective study. This option looks at the past by reviewing historical information, such as medical records, to determine if there is a pattern in the data that is useful.

List of the Cons of Longitudinal Studies

1. The structure makes it possible for one person to change everything.
Longitudinal studies have a robust reliance on the individual interpretations that researchers develop after making their observations. That makes it possible for personal bias, inexperience, or a mistake to inadvertently alter the data being collected in real-time situations. This issue makes it possible for the information to be invalid without researchers realizing that this disadvantage is present in their work. Even if there are numerous people involved with a project, it is possible for a single person to disrupt potentially decades of work because of their incorrect (and possibly inadvertent) approach.

2. It is more expensive to perform longitudinal studies than other research methods.
This disadvantage typically applies to the research studies which are designed to take longer periods of time to collect relevant information. Because observations may last for several years (if not decades), the organizations which are behind the effort of information retention can discover that their costs can be up to 50% higher in some situations when they choose this method over the other options that are available. Although the value of the research remains high, some may find the cost to be a significant barrier to cross.

3. The information collected by researchers may have few controls.
The real-time observational data that researchers collect during longitudinal studies is both informative and efficient from a cost perspective when looking at short-term situations. One of the problems that this method encounters is that the information being collected comes from a relatively small number of individuals. Unless it is built into the rules for collection, there may be no controls in place for environmental factors or cultural differences between the individuals involved.

4. It can be challenging for longitudinal research to adapt to changes.
There is sometimes no follow up to identify changes in thinking or operations that occur when using longitudinal studies as the primary basis of information collection. Researchers sometimes fail to compare attitudes, behaviors, or perceptions from one point of time to another. Most people change as time passes because they have more information available to them upon which they can draw an opinion. Some people can be very different today than they were 10 years ago. Unless the structures are flexible enough to recognize and adapt to this situation, then the data they gather may not be as useful as it should be.

5. Longitudinal studies often require a larger sample size.
Researchers use longitudinal studies to develop a recognition for patterns and relationships. That means there is a large amount of data that must be collected from numerous individual sources to draw meaningful connections to the topic under study. If there is not a significant sample size available to researchers for the project, then there may not be enough information available to find specific conclusions.

Even when there is enough data present for researchers to use, the sheer size of what they collect can require data mining efforts that can take time to sort out.

6. Some people do not authentically participate in longitudinal studies.
As with any other form of research that is performed today, you will encounter individuals who behave artificially because they know they are part of a longitudinal study program. When this issue occurs, then it becomes challenging for researchers to sort out what the authentic and inauthentic emotions, thoughts, and behaviors are from each other. Some participants may try to behave in the ways that they believe the researchers want to create specific results.

A study by psychologist Robert S. Feldmen and conducted by the University of Massachusetts found that 60% of people lie at least once during a 10-minute conversation. The average person will lie 2-3 times during that discussion. The content of fibs varies between men and women, trying to make themselves look better or to make the person they are talking to feel good respectively. Researchers must recognize this trait early to remove this potential disadvantage.

7. Longitudinal studies rely on the skill set of the researchers.
The data that longitudinal studies collects is presented in real-time to researchers, which means it relies on their individual skills to make it useful. Those who are tasked with this job must follow a specific set of steps to ensure that there is authenticity and value to what they observe. Even if you offer step-by-step guidelines on how to perform the work, two different researchers may interpret the instructions differently, which can then lead to an adverse result. The personal views of the information being collected can also impact the results in ways that are not useful.

8. The data that is collected from longitudinal studies may not be reliable.
Although the goal of longitudinal studies is to identify patterns, inaccuracies in the information collected can lead to incorrect interpretations of choices, thoughts, and behaviors. All it takes is one piece of data to be inaccurate for the results to be impacted in negative ways. It is possible that the findings of the research could be invalidated by just one incorrect interpretation of a real-time result. That is why any conclusion made using this method is often taken with a “grain of salt” with regard to its viability.

9. There is a time element to consider with longitudinal studies.
Researchers may find that it requires several years of direct observation before any meaningful data becomes available through longitudinal studies. Some relationships or observable behaviors may never occur even though it seems like they should, which means this time investment may never offer dividends. These studies must have the means to maintain continuously open lines of communication with all of the involved parties to ensure that the quality of the data remains high throughout the entire effort.

10. Longitudinal studies always offer a factor of unpredictability.
Because the structure of longitudinal studies will follow the same individuals over an extended time period, what happens to each person outside of the scope of the research can have a direct impact on the eventual findings that researchers develop. Some people may choose to stop participating in the study altogether, which may reduce the validity of the final result when published. It is possible for some individuals or households to shift their demographic profile so that they are no longer viable candidates for the research. Unless these factors are included in the initial structure of the project, then the findings that are developed from the work could be invalid.

The pros and cons of longitudinal studies provides us with a valuable foundation of data that makes it possible to recognize long-term relationships, determine their value, and where it may be possible to make healthy changes in numerous fields. There are certain risks to consider with this process that may create unpredictable outcomes, but it is also through this research method that we will likely find new ways to transform numerous scientific and medical fields in the future.

About the Author of this Blog Post
Crystal Ayres has served as our editor-in-chief for the last five years. She is a proud veteran, wife and mother. The goal of ConnectUs is to publish compelling content that addresses some of the biggest issues the world faces. If you would like to reach out to contact Crystal, then go here to send her a message.