What is the Difference Between Longitudinal and Cross Sectional Study

The main difference between longitudinal and cross sectional study is that longitudinal studies look at variables repeatedly over a period of time while cross sectional studies look at variables at a particular point in time.

Both longitudinal studies and cross sectional studies are two types of observational studies. These are useful for studying different types of issues and answering different research questions.

Key Areas Covered

1. What is a Longitudinal Study
     – Definition, Features, Method
2. What is a Cross Sectional Study
     – Definition, Features, Method
3. Similarities Between Longitudinal and Cross Sectional Study
      – Outline of Common Features
4. What is the Difference Between Longitudinal and Cross Sectional Study
    – Comparison of Key Differences

Key Terms

Longitudinal Study, Cross Sectional Study, Observational Study

What is a Longitudinal Study

A longitudinal study involves repeatedly examining the same subjects to detect changes that may occur over a period of time. This time period may be as short as a few weeks or as long as several decades. This is a type of observational research where the researcher does not interfere with the subjects. Since the research extends beyond a single moment in time, the researcher can identify changes or developments in the target population, at both group and individual levels, and establish sequences of events.

Longitudinal studies are mainly used in economics, epidemiology and medicine. They are a type of correlational studies. Moreover, there are three main types of longitudinal studies as panel study, cohort study and retrospective study.

Panel study – a study that provides longitudinal data on a group of people

Cohort study – a longitudinal study in which the sample share a defining characteristic such as birth year, geographical area, etc.

Retrospective study – a study that involves observing past events by analyzing historical information such as medical records.

Pros and Cons of Longitude Studies

Pros

• Provide unique insights which cannot be obtained in any other way
• Useful in observing phenomena related to development and lifespan
• Helps to establish a sequence of events
• Can also be done with a few participants

Cons

• Tends to be expensive and time-consuming

What is a Cross Sectional Study

A cross sectional study is a type of observational study in which a researcher collects data from many different individuals at a specific point in time. Researchers can use these studies to analyze several characteristics, such as income, gender, age, at once. Moreover, they give a glimpse into the prevailing characteristics in a population and can provide information about what is currently happening in the population. Therefore, cross sectional studies can provide a snapshot of a population or society at a specific moment. In fact, cross sectional studies are the opposite of longitudinal studies.

Although cross sectional studies are used to analyze the characteristics in a society or community, they cannot analyze cause-and-effect relationship between variables. They also help to gather preliminary data for further research.

Pros and Cons of Cross Sectional Studies

Pros

• Allows researchers to gather information very quickly
• Does not take much time
• Multiple variables can be observed at once
• A helping hand to further study

Cons

• Cannot determine cause-and-effect relationships
• Cannot observe development over a period of time

Similarities Between Longitudinal and Cross Sectional Study

• Both longitudinal studies and cross sectional studies are observational research studies.
• Moreover, in both studies, the researcher does not interfere with the subjects.

Difference Between Longitudinal and Cross Sectional Study

Definition

A longitudinal study is an observational study that involves repeatedly examining the same subjects to detect changes that may occur over a period of time while a cross sectional study is a type of observational study that involves collecting data from many different individuals at a specific point in time.

Time

Longitudinal studies look at variables repeatedly over a period of time while cross sectional studies look at variables at a particular point in time.

Sampling

Moreover, longitudinal studies observe the same sample while cross sectional studies observe different samples.

Result

While longitudinal studies observe change at both group and individual level, cross sectional studies give a snapshot of the population at a specific point in time.

Time and Cost

In addition, longitudinal studies tend to be expensive and time-consuming while cross sectional studies are not expensive and do not take a lot of time.

Cause-and-Effect Relationships

Longitudinal studies can study cause-and-effect relationship between variables while cross sectional studies cannot.

Conclusion

The main difference between longitudinal and cross sectional study is that longitudinal studies look at variables repeatedly over a period of time while cross sectional studies look at variables at a particular point in time.

Reference:

1. Cherry, Kendra. “How Longitudinal Research Is Used in Psychology.” Verywell Mind, 2 May 2020, Available here.
2. Thomas, Lauren. “Cross-Sectional Study: Definitions, Uses & Examples.” Scribbr, 5 June 2020, Available here.

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1. “Australia BF rates2004” By KellyMom.com – Bonyata.com (CC BY-SA 4.0) via Commons Wikimedia
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