Читать книгу The Research Experience - Ann Sloan Devlin - Страница 138

The term experimental mortality signifies not only that people have dropped out but also that participants have dropped out of a study in a nonrandom manner (e.g., more from the control than from the intervention group). That situation creates a problem because those who remain in the study no longer represent our original balance of random assignment to condition. Dropping out of studies commonly occurs in longitudinal research, where participants are followed over long periods of time (see Chapter 7). One well-known exception to longitudinal dropouts is the work involving what are known as Terman’s Termites, a group of gifted youngsters followed by the Stanford researcher Lewis Terman for decades (Leslie, 2000).

Experimental mortality: One of Campbell and Stanley’s (1963) threats to internal validity in which people drop out of studies in a nonequivalent manner (e.g., more older adults than younger adults drop out of the intervention than out of the control group).

Selection–maturation interaction: One of Campbell and Stanley’s (1963) threats to internal validity in which with quasi-experimental designs with multiple groups, some preexisting aspect of the groups might produce differences in the rate of change unrelated to the variable of interest.

Demand characteristics: “Cues available to participants in a study that may enable them to determine the purpose of the study, or what is expected by the researcher” (Corsini, 2002, p. 262).