What does the term 'attrition' refer to in research contexts?

The term 'attrition' in research contexts specifically refers to the loss of participants over time during a study. This phenomenon is particularly pertinent in longitudinal studies, where researchers track the same individuals across an extended period. Attrition can occur for various reasons, such as participants dropping out due to personal circumstances, lack of interest, or difficulties in maintaining contact.

Understanding attrition is crucial because it can significantly impact the validity and reliability of a study's outcomes. High levels of attrition may lead to biased results, as the remaining participants might not represent the original sample adequately, thus affecting the generalizability of the findings. Researchers often aim to minimize attrition through various strategies, such as maintaining regular communication with participants or providing incentives for continued participation.

The other options relate to different aspects of research but do not define attrition specifically. For example, the inclusion of too many participants pertains to sample size rather than participant loss, while a change in research methodology refers to alterations in how the study is conducted. Gathering quantitative data speaks to the type of data collected and does not relate to the issue of participant retention over time.