DEFINITION 1: A data-collection strategy in which data are collected from the same participants at different points in time. The purpose is to draw conclusions about individual change over time.
SOURCE: Hickman, Richard (2013). Cambridge Handbook of Educational Abbreviations & Terms (C.H.E.A.T.), Faculty of Education, University of Cambridge.
DEFINITION 2: Scientific study of the development of individual or collective behavior in order to highlight the characteristics of stages of changes compared to earlier stages.
SOURCE: IIEP Glossary, IIEP-UNESCO.