Attrition in research refers to the loss of participants or data over the course of a study. This can happen for a variety of reasons, such as participants dropping out, becoming unavailable, or failing to complete required tasks or assessments. Attrition can have a negative impact on the validity and generalizability of study results, as well as on the overall research process. Researchers often aim to minimize attrition by implementing strategies to retain participants and ensure the integrity of the study.