Betweenperson

Between-person is a term used in psychology, sociology, and related fields to describe differences or effects that occur across individuals rather than within a single person over time or across situations. It is often used to distinguish between interindividual differences (how people differ from one another) and intraindividual dynamics (how a single person changes over time).

In research design and analysis, between-person effects are typically studied using models that separate variability into between-subject and within-subject components. Between-person variance reflects stable differences between individuals, such as average levels of a trait or behavior across the study period. Within-person variance captures how a person fluctuates around their own average over time or across contexts. This distinction is important in multilevel modeling, longitudinal analyses, and cross-sectional studies, where researchers aim to understand how associations differ when comparing different people versus examining changes within the same person.

An example: in a study of work satisfaction and performance, a between-person effect would indicate that employees who, on average, report higher job satisfaction also tend to have higher average performance across the study period. A within-person effect would show that on days when a given employee feels more satisfied than usual, their performance that day may also improve.

Related concepts include within-person effects, between-subjects designs, and interindividual differences. Between-person analyses are complementary to within-person analyses, each illuminating different aspects of human behavior.