Which term describes participant dropout during a study that affects the validity of the results?

The term that describes participant dropout during a study, which can affect the validity of the results, is mortality. In research, particularly in longitudinal studies or trials that span an extended period, mortality refers to the loss of participants due to various factors, including moving away, losing interest, or experiencing adverse events related to the study.

When participants drop out, it can lead to biased outcomes or reduced statistical power because the remaining participants may not represent the original sample's characteristics. This dropout can distort the results, as the reasons for dropout may be systematically related to the study's variables or outcomes. For example, if individuals who are experiencing negative effects tend to leave the study more than those who are not, the final results may underreport the negative outcomes of the intervention being studied.

Other terms in the list refer to different concepts in research. Experimenter bias refers to the influence that a researcher’s expectations may have on the outcome of a study. Ecological validity pertains to the extent to which research findings can be generalized across settings, populations, or times. The Hawthorne effect describes a situation where individuals modify their behavior in response to being observed in a study, rather than due to the treatment itself. Understanding mortality is crucial for maintaining the integrity and validity of