Good but bittersweet news for fans of The Americans. The hit FX drama series, which focuses on Russian spies living undercover as Americans in the 1980s, is currently in its fourth season, with three more episodes to go, and FX has renewed the critically acclaimed show for not one but two more seasons!
Experiments that take advantage of natural occurrences are quasi-experiments, for example, comparing achievement level of first-born children with that of later-born children; or comparing student performance at two schools, one of which has a lower student-teacher ratio.
In quasi-experimental designs, outcomes may only be measured at the end of the study (rather than at the beginning and end), there may not be a control group, or patients may be assigned to the control and treatment groups by methods other than randomization.n 1979, in their classic textbook Quasi-Experimentation: Design and Analysis Issues for Field Settings Cook and Campbell describe quasi-experimental designs and their limitations. That work is the basis for the following discussion.