pretest–posttest design

a research design in which the same assessment measures are given to participants both before and after they have received a treatment or been exposed to a condition, with such measures used to determine if there are any changes that could be attributed to the treatment or condition. A more complete version in which participants are randomly assigned to a treatment group or a control group is a pretest–posttest control-group design: All individuals are assessed at the beginning of the study, the intervention is presented to the treatment group but not the control, and then all individuals are measured again. The presence of the control group allows the researcher to identify any preexisting disparities between the groups and thus to more definitely attribute differences between the pre- and posttest scores to the treatment of interest. Also called before–after design; pre–post design.