In cross-sectional research, a researcher compares multiple segments of the population at the same time. If they were interested in people's dietary habits, the researcher might directly compare different groups of people by age. Instead of following a group of people for 20 years to see how their dietary habits changed from decade to decade, the researcher would study a group of 20-year-old individuals and compare them to a group of 30-year-old individuals and a group of 40-year-old individuals.

Thus, cross-sectional research requires a shorter-term investment. However, it is also limited by differences that exist between the different generations (or cohorts) that have nothing to do with age per se, but rather reflect the social and cultural experiences of different generations of individuals that make them different from one another. This situation reflects a concept known as a cohort effect—results are impacted by the characteristics of the cohorts being studied. Here, a cohort is defined as a group of people who share common characteristics or experiences, such as birth year or term they started college.

This text is adapted from OpenStax, Psychology. OpenStax CNX.