Campbell and Stanley stated that quasi-experimental studies are “well worth
employing where more efficient probes are unavailable” (1966, p. 205). To determine if students who completed
one credit hour CAI session in addition to attending traditional lectures outperform students who only attend
regular lectures, two different sections of introductory statistics courses were matched on confounding variables
recommended by Tobias (1987); Trowbridge (1987); Liefeld and Herrmann (1990); Duncan (1993) and
Worthington et al., (1996).