What does 'attrition' mean in a research study context?

In the context of a research study, 'attrition' refers to the loss of participants during the course of a study. This can occur for various reasons, such as participants dropping out, becoming unavailable, or failing to complete the study. Attrition is a critical concern in research because it can lead to biased results and affect the study's validity. When participants leave the study, the remaining sample may no longer accurately represent the original population, which can skew findings and lead to incorrect conclusions.

Understanding attrition is vital for researchers as they develop strategies to minimize its impact, such as using follow-up procedures to retain participants or employing statistical methods to adjust for incomplete data. Unlike the other options, which do not accurately reflect the concept of attrition, this definition encapsulates a significant challenge in maintaining the integrity of a research study's outcomes.