Adrought in california created the opportunity for a quasi-experiment on the effectiveness of fines on water conservation (agras et al., 1980). three comparable cities were considered - two that instituted fines at different times and a third that did not. water consumption data for the 3 years before the onset of the fines were used as baseline and subsequent consumption data were gathered through the end of the drought. effectiveness of fines was assessed by examining consumption the following month. in this study, researchers capitalized on real-life opportunities to study phenomena. therefore, they maximized which type of validity?
a. statistical
b. construct
c. internal
d. external