Longitudinal studies are a type of research or survey that primarily uses the method of observation, which entails that they do not involve interfering with the subjects in any means. These studies are also unique in a way that they follow a certain timeline that is entirely dependent on the respondents, which means that data collection could take years depending on the exact timetable put in place. Most of the time, they are used by psychologists who are looking to measure or identify the impact therapy can have over time, involving long time frames and vast amounts of data.
Now, like any other type of method in conducting research, longitudinal studies also come with certain disadvantages, while they offer obvious advantages. Here are important things to take note when planning to use this methodology:
List of Advantages of Longitudinal Studies
1. They are effective in determining variable patterns over time.
Because these studies involve the use and collection of data in long periods of time, they can determine patterns efficiently. By using them, it would be possible for researchers to learn more about cause and effect relationships and make connections in a clearer manner. Aside from this, remember that more data over longer periods of time will allow for more concise and better results. These studies are considered highly valid for determining long-term changes and are unique in themselves when it comes to being able to provide useful data about these individual changes.
2. They can ensure clear focus and validity.
With a clear focus, longitudinal studies would let us observe how a certain set of circumstances or an end state would come to be. And while it is natural for people not to remember past events, this problem can be addressed by means of actual recording that ensures a high level of validity.
3. They are very effective in doing research on developmental trends.
As mentioned above, these studies are often used in psychology to conduct research on developmental trends across life spans. They are used in sociology to study life events throughout lifetimes or generations. This is so because, unlike cross-sectional studies where different individuals with similar characteristics are being compared, longitudinal studies would track the same people, which means that the differences observed in a group will be less likely to be the result of a change or difference in culture across generations.
4. They are more powerful than cross-sectional studies.
As they utilize the observation method without manipulating the state of the world, longitudinal studies have been argued to having less power in terms of detecting causal relationships compared with experiments. However, they are known to have more power than cross-sectional studies when it comes to excluding time-invariants and unobserved individual differences and when it comes to observing a certain event’s temporal order, as they use repeated observations at individual levels.
5. They are highly flexible.
Longitudinal studies are often observed to allow flexibility to occur. This means that the focus they use can be shifted while researchers are collecting data.
6. They can provide high accuracy when observing changes.
With their quality of being the perfect method to conduct research on developmental trends, these studies can make observation of changes more accurate, making them as the usual option in various fields. In medicine, for example, longitudinal studies are used to discover predictors or indicators of certain diseases, while in advertising, they are used to determine changes that a campaign has made in the behavior of consumers who belong to its target audience and have seen the advertisement.
List of Disadvantages of Longitudinal Studies
1. They require huge amounts of time.
Time is definitely a huge disadvantage to any longitudinal study, as it typically takes a substantial amount of time to collect all the data that is required. Also, it takes equally long periods to gather results before the patterns can even start to be made.
2. They risk gathering data that is not 100% reliable.
While data is collected at multiple points in this method of conducting research, you cannot pre-determine and take into account the observation periods regardless of what happens between these points. Aside from this, respondents would unknowingly change their qualitative responses over time to better suit what they see as the objective of the observer. Generally, the process involved in longitudinal studies will change how respondents and subjects the questions that are being used.
3. They would risk experiencing panel attrition.
One of the biggest disadvantages of conducting longitudinal studies is panel attrition. This means that, if researchers are only relying upon the same group of subjects for a research that takes place at certain points in time in years, then there is the possibility that some of the subjects would no longer be able to participate because of various reasons, such as changes in contact details, refusal, incapacity and even death, which cuts down the usable data to be drawn to formulate the conclusion.
4. They require a large sample size.
Another disadvantage that makes longitudinal studies not the perfect option to conduct research is that they typically require large sample sizes. So, you must have a large number of cooperating subjects for your research or else it will not realize or be valid.
5. They can be more expensive compared with cross-sectional studies.
Cross-sectional studies are known to be more affordable compared with longitudinal studies and are much quicker in reaching an observational conclusion as they use fewer touch points. Considering that they utilize a sample size that is carefully chosen, rather than subsets, the former can also be more of a help in representing entire populations. The former is observed to be very beneficial when it comes to considering a change in policy, unlike the latter.
A lot of researchers encourage and welcome the use of longitudinal data sets, where they can apply and access data via relevant pathways that are set out by the groups that hold such information. However, longitudinal studies also have some limitations. Based on the advantages and disadvantages listed on this article, do you think these method are more helpful to society than not?
Keith Miller has over 25 years of experience as a CEO and serial entrepreneur. As an entrepreneur, he has founded several multi-million dollar companies. As a writer, Keith's work has been mentioned in CIO Magazine, Workable, BizTech, and The Charlotte Observer. If you have any questions about the content of this blog post, then please send our content editing team a message here.