What Is a Cross-Sectional Study?

The Advantages and Challenges of Cross-Sectional Studies

Cross-sectional studies
Cross-sectional studies offer a snapshot of what is present in a group at a specific point in time.. Ale Neri / Moment / Getty Images

A cross-sectional study involves looking at people who differ on one key characteristic (such as age) at one specific point in time. The data is collected at the same time from people who are similar on other characteristics but different on a key factor of interest such as age, income levels and geographic locations. Participants are usually separated into groups known as cohorts. For example, researchers might create cohorts of participants who are in their 20s, 30s, and 40s.

This type of study uses different groups of people who differ in the variable of interest but who share other characteristics such as socioeconomic status, educational background, and ethnicity. Cross-sectional studies are often used in developmental psychology, but this method is also utilized in many other areas including social science and education.

For example, researchers studying developmental psychology might select groups of people who are remarkably similar in most areas but differ only in age. By doing this, any differences between groups can presumably be attributed to age differences rather than to other variables.

Cross-sectional studies are observational in nature and are known as descriptive research, not causal or relational. Researchers record the information that is present in a population, but they do not manipulate variables.

This type of research can be used to describe characteristics that exist in a community, but not to determine cause-and-effect relationships between different variables.

These methods are often used to make inferences about possible relationships or to gather preliminary data to support further research and experimentation.

Defining Characteristics of Cross-Sectional Studies

Some of the key characteristics of cross-sectional studies:

  • Takes place at a single point in time
  • Does not involve manipulating variables
  • Allows researchers to look at numerous things at once (age, income, gender)
  • Often used to look at the prevailing characteristics in a given population

Think of a cross-sectional study as a snapshot of a particular group of people at a given point in time. Unlike longitudinal studies that look at a group of people over an extended period, cross-sectional studies are used to describe what is happening at the present moment.

This type of research is frequently used to determine the prevailing characteristics in a population at a given point in time. For example, a cross-sectional study might be used to determine if exposure to specific risk factors might correlate with particular outcomes.

A researcher might collect cross-sectional data on past smoking habits and current diagnoses of lung cancer, for example. While this type of study cannot demonstrate cause-and-effect, it can provide a quick look at correlations that may exist at a particular point in time.

The Advantages of Cross-Sectional Studies

So when might a researcher decide to utilize a cross-sectional design? Like other types of research, cross-sectional studies have a number of advantages as well as challenges.

Cross-sectional studies are usually relatively inexpensive and allow researchers to collect a great deal of information quite quickly. Data is often obtained using self-report surveys and researchers are often able to amass large amounts of information from a large pool of participants. Another benefit is that researchers can collect data on some different variables to see how differences in sex, age, educational status and income might correlate with the critical variable of interest.

While cross-sectional studies cannot be used to determine causal relationships that can provide a useful springboard to further research. When looking at a public health issue, such as whether a particular behavior might be linked to a particular illness, researchers might utilize a cross-sectional study to look for clues that will serve as a useful tool to guide further experimental studies.

For example, researchers might be interested in learning how exercise influences cognitive health as people age. They might collect data from different age groups on how much exercise they get and how well they perform on cognitive tests. Performing such a study might give researchers clues about the types of exercise that might be the most beneficial to cognitive health and inspire further experimental research on the subject.

Potential Challenges Posed by Cross-Sectional Studies

While the design sounds relatively straightforward, finding participants who are very similar except in one specific variable can be difficult. Cross-sectional studies generally require a large number of participants, so it is more likely that there will be small differences among participants. While such differences might seem minor, they can influence the study's findings.

Also, groups can be affected by cohort differences that arise from the particular experiences of a unique group of people. Individuals born during the same period may share important historical experiences while people born in a given geographic region may share experiences limited solely to their physical location. Individuals who were alive during the invasion of Pearl Harbor, Vietnam, or 9/11 might have shared experiences that make them different from other age groups, for example.

Cross-Sectional Vs. Longitudinal Studies

This type of research differs from longitudinal studies in that cross-sectional studies are designed to look at a variable at a particular point in time. Longitudinal studies involve taking multiple measures over an extended period while cross-sectional research focuses on looking at variables at a given point in time.

As you might imagine, longitudinal studies tend to require more resources and are often more expensive that cross-sectional resources. They are also more likely to be influenced by what is known as selective attrition. Some individuals are simply more likely to drop out of a study than others, which can influence the validity of a longitudinal study.

One of the advantages of cross-sectional studies is that since data is collected all at once, it is less likely that participants will quit the study before data is fully collected.

References:

Gratton, C., & Jones, I. (2004). Research methods for sports studies. London: Routledge.

Trochim, W.M.K. (2006). Time in research. Research Methods Knowledge Base. Web Center for Social Research Methods. http://www.socialresearchmethods.net/kb/timedim.php

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