Cross-sectional vs Longitudinal research design

Recently I am working on a project that urges me to review a lot of journal articles. Cross-sectional research and longitudinal research were one of the many things I came across. Below is just the very basic differences between the two that I learnt.

In cross- sectional research we don’t manipulate any variables, and we cannot make causal statements about the relationships between variables, so it doesn’t make sense to talk of dependent and independent variables because all variables are dependent variables in a sense. The researcher simply records information of the samples in the population without manipulating the environment in any manner and it is comparing two populations at any given point of time.

An example of cross-sectional research is a study by NCBI on the association between beer and obesity. A random sample of 1141 men and 1212 women aged 25-64 yrs completed a questionnaire and underwent a short examination in a clinic. Intake of beer, wine and spirits during a typical week, frequency of drinking, and number of other factors were measured by a questionnaire. For more details refer the link: Beer and obesity: a cross-sectional study.

In longitudinal research, the researcher again collects information of the sample in a population without modifying the environment. However, the researcher conducts several observations of the same sample multiple times. In this way the researchers are able to detect changes in the target population by observations of the sample data over time.

An example of longitudinal research was designed by the Canadian Longitudinal Study on Aging (CLSA) to follow approximately 50,000 men and women between the ages of 45 and 85 for at least 20 years. CLSA researchers then gathered information on biological, medical, psychological, social, lifestyle and economic factors by studying these sample then then made significant inferences about the target population. For more details refer the link: Canadian Longitudinal Study on Aging (CLSA).