Cross-sectional & Longitudinal Research

Cross-sectional

A research design that collects data at one point in time from different groups to compare them.

Longitudinal

A research design that follows the same participants over a long period of time to study changes over time.

Cohort

A group of individuals who share a common characteristic or experience within a defined time period.

Cohort effects

Differences observed between cohorts that arise from their distinct experiences or backgrounds, rather than age or development.

Cross-generational problem

The issue in longitudinal research where findings from one generation may not apply to future generations due to changing contexts or experiences.

Practice effects / test effects

Changes in participants’ performance on repeated tests due to familiarity with the test rather than true changes in ability.

Selective survival

The phenomenon where only certain individuals survive or remain in a study, possibly influencing the results.

Attrition / Selective drop out

When participants drop out of a study over time, potentially biasing results if those who drop out differ significantly from those who remain.

Accelerated longitudinal study

A research design that collects data from multiple cohorts at different stages to simulate a long-term study in a shorter period.

Cross-lagged correlations

A method in longitudinal research that examines the relationship between variables measured at different times to explore cause-and-effect.

Prospective

A research design that follows participants into the future to observe outcomes or effects of certain variables.

Retrospective

A research design that looks backward, gathering data from past events or experiences to understand current conditions or outcomes.